Self-mutual capacitance detection circuit, method, chip and device

Abstract

The present application discloses a self-mutual capacitance detection circuit, method, chip and device, which relates to but is not limited to the field of capacitance detection technology, wherein a self-mutual capacitance detection circuit includes: a sensing module, an excitation module and a detection module; the sensing module includes mutual capacitance and self capacitance; the excitation module is used to generate an excitation signal; the detection module is used to detect mutual capacitance and self capacitance; the input end of the sensing module is connected to the excitation module, and the output end of the sensing module is connected to the detection module. The self-mutual capacitance detection circuit, method, chip and device of the present application can simultaneously detect the self-capacitance and mutual capacitance of the sensing element, increase the signal amount output by the circuit, thereby increasing the signal-to-noise ratio and improving the accuracy of the detection result.

Description

Technical Field

[0001] The embodiments of the present application relate to, but are not limited to, the field of capacitance detection technology, and in particular, to a self-mutual capacitance detection circuit, method, chip, and device. Background Art

[0002] Capacitive touch screens have been increasingly used in various electronic equipment fields due to their durability, fast response speed, space saving, and high light transmittance. Capacitive touch screens use transparent indium tin oxide (ITO) materials to form an electrode array on the surface of a glass substrate. According to different detection principles, capacitive touch screens are divided into self-capacitive touch screens and mutual-capacitive touch screens: self-capacitive touch screens determine the touch position of the touch object on the touch screen by detecting the change in capacitance between the electrode and the ground before and after the touch; mutual-capacitive touch screens determine the touch position of the touch object on the touch screen by detecting the change in capacitance between the two groups of electrodes before and after the touch. That is, self-capacitive touch screens detect touch by detecting the change in capacitance between the electrode and the ground, while mutual-capacitive touch screens detect touch by detecting the change in capacitance between the two electrodes.

[0003] Current capacitance detection technology mainly detects changes in the self-capacitance of the sensing element or changes in the mutual capacitance between two electrodes in the sensing element. When a conductor (finger or fingerprint ridge) approaches the sensing element, the mutual capacitance and self-capacitance of the sensing element will change. The farther the conductor is from the sensing element, the smaller the change in the self-capacitance and mutual capacitance of the sensing element. If only the self-capacitance or mutual capacitance of the sensing element is detected, the change in the signal is too small and is easily interfered by noise, resulting in possible erroneous detection results. Summary of the invention

[0004] The embodiment of the present application aims to solve one of the technical problems existing in the prior art to at least a certain extent. To this end, the embodiment of the present application proposes a self-mutual capacitance detection circuit that can simultaneously detect the self-capacitance and mutual capacitance of the sensing element, increase the signal-to-noise ratio, and thus improve the accuracy of the detection result.

[0005] The embodiment of the present application also provides a self-mutual capacitance detection method.

[0006] The embodiment of the present application also provides a chip.

[0007] The embodiment of the present application also provides a device.

[0008] In a first aspect, an embodiment of the present application provides a self-mutual capacitance detection circuit, the circuit comprising: a sensing module, an excitation module and a detection module;

[0009] The sensing module includes mutual capacitance and self capacitance;

[0010] The excitation module is used to generate an excitation signal;

[0011] The detection module is used to detect mutual capacitance and self capacitance;

[0012] The input end of the sensing module is connected to the excitation module, and the output end of the sensing module is connected to the detection module.

[0013] The self-mutual capacitance detection circuit of the embodiment of the present application can simultaneously detect the self-capacitance and mutual capacitance of the sensing element, thereby increasing the signal amount output by the circuit, thereby increasing the signal-to-noise ratio and improving the accuracy of the detection result.

[0014] According to some other embodiments of the present application, the self-mutual capacitance detection circuit, the excitation module includes: a first excitation module and a second excitation module;

[0015] The first excitation module includes a first excitation source and a second excitation source, the first excitation source is connected to the sensing module via a first switch; the second excitation source is connected to the sensing module via a second switch;

[0016] The second excitation module includes a third excitation source and a fourth excitation source. The third excitation source is connected to the sensing module via a third switch; and the fourth excitation source is connected to the sensing module via a fourth switch.

[0017] In the self-mutual capacitance detection circuit of the embodiment of the present application, an excitation source generates an excitation signal, and the connection between the excitation source and the sensing module is controlled by a switch, so as to facilitate the control of the input of the excitation signal.

[0018] According to some other embodiments of the present application, the self-mutual capacitance detection circuit, the sensing module includes: a first transmitting electrode, a second transmitting electrode and a receiving electrode;

[0019] The first transmitting electrode is coupled to the receiving electrode to form a mutual capacitance;

[0020] The second transmitting electrode is used to transmit an excitation signal to the conductor, and the conductor is coupled to the receiving electrode to form a self-capacitance;

[0021] The first transmitting electrode is connected to the first switch and the second switch respectively, the second transmitting electrode is connected to the third switch and the fourth switch respectively, and the receiving electrode is connected to the detection module.

[0022] In the self-mutual capacitance detection circuit of the embodiment of the present application, the first transmitting electrode in the sensing module is coupled with the receiving electrode to form a mutual capacitance, the second transmitting electrode is used to transmit an excitation signal to the conductor, and the conductor is coupled with the receiving electrode to form a self-capacitance, which provides the necessary conditions for realizing the simultaneous detection of mutual capacitance and self-capacitance.

[0023] According to some other embodiments of the present application, the self-mutual capacitance detection circuit, the detection module includes: an operational amplifier, a feedback capacitor and a feedback loop switch;

[0024] The non-inverting input terminal of the operational amplifier is connected to a reference voltage source, and the reference voltage source is used to provide a reference voltage for the operational amplifier;

[0025] The inverting input terminal of the operational amplifier is respectively connected to one end of the feedback capacitor, one end of the feedback loop switch and the output end of the sensing module;

[0026] The other end of the feedback capacitor is connected to the output end of the operational amplifier, and the other end of the feedback loop switch is connected to the output end of the operational amplifier.

[0027] The self-mutual capacitance detection circuit of the embodiment of the present application connects the sensing signal to the inverting input terminal of the operational amplifier and uses the feedback capacitor to bias the operational amplifier, which can remove capacitive background noise while amplifying the signal.

[0028] According to some other embodiments of the self-mutual capacitance detection circuit of the present application, the circuit further includes an adjustment module, the adjustment module is used to adjust the signal amount output by the sensing module, the signal amount includes the mutual capacitance signal amount and the self-capacitance signal amount;

[0029] The regulating module is connected to the output end of the sensing module.

[0030] The self-mutual capacitance detection circuit of the embodiment of the present application can increase the output range of the signal quantity by adding an adjustment module to adjust the sensing signal, thereby improving the applicability of the circuit.

[0031] According to some other embodiments of the self-mutual capacitance detection circuit of the present application, the adjustment module includes: an adjustable capacitor, a first adjustable excitation source and a second adjustable excitation source;

[0032] The first adjustable excitation source is connected to one end of the adjustable capacitor through a first adjustment switch;

[0033] The second adjustable excitation source is connected to one end of the adjustable capacitor through a second adjustment switch;

[0034] The other end of the adjustable capacitor is connected to the output end of the sensing module.

[0035] The self-mutual capacitance detection circuit of the embodiment of the present application controls the input of the excitation signal through a switch and adjusts the sensing signal using an adjustable capacitor, thereby achieving real-time adjustment of the sensing signal.

[0036] In a second aspect, an embodiment of the present application provides a self-mutual capacitance detection method, which is used in the self-mutual capacitance detection circuit of some embodiments of the present application, and the method includes: a reset step and a charge transfer step;

[0037] The resetting step includes: performing reset control on the circuit, calculating the total charge of the circuit, and obtaining a first total charge;

[0038] The charge transfer step includes: performing charge transfer control on the circuit, calculating the total charge amount of the circuit, and obtaining a second total charge amount;

[0039] According to the charge conservation relationship between the first total charge amount and the second total charge amount, the output signal amount of the circuit is obtained.

[0040] The self-mutual capacitance detection method of the embodiment of the present application can simultaneously detect the self-capacitance and mutual capacitance of the sensing element, thereby increasing the signal amount output by the circuit, thereby increasing the signal-to-noise ratio and improving the accuracy of the detection result.

[0041] According to some other embodiments of the self-mutual capacitance detection method of the present application, the method also includes an adjustment step, and the adjustment step includes: adjusting and controlling the circuit to adjust the first total charge amount and the second total charge amount.

[0042] The self-mutual capacitance detection method of the embodiment of the present application can increase the output range of the signal quantity by adding an adjustment step to adjust the sensing signal, thereby improving the applicability of the circuit.

[0043] In a third aspect, an embodiment of the present application provides a chip, which includes the self-mutual capacitance detection circuit of some embodiments of the present application.

[0044] The chip of the embodiment of the present application can simultaneously detect the self-capacitance and mutual capacitance of the sensing element, thereby increasing the signal amount output by the circuit, thereby increasing the signal-to-noise ratio and improving the accuracy of the detection result.

[0045] In a fourth aspect, an embodiment of the present application provides a device, the device comprising at least one processor, and a memory communicatively connected to the at least one processor; wherein,

[0046] The memory stores instructions executable by at least one processor, the instructions being executed by at least one processor to enable the at least one processor to:

[0047] The self-mutual capacitance detection method of some embodiments of the present application is implemented.

[0048] The device of the embodiment of the present application can simultaneously detect the self-capacitance and mutual capacitance of the sensing element, thereby increasing the signal amount output by the circuit, thereby increasing the signal-to-noise ratio and improving the accuracy of the detection result. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 is a circuit structure block diagram of a specific embodiment of a self-mutual capacitance detection circuit in the embodiment of the present application;

[0050] Figure 2 is a circuit structure block diagram of another specific embodiment of a self-mutual capacitance detection circuit in the embodiment of the present application;

[0051] Figure 3 is a circuit schematic diagram of a specific embodiment of a self-mutual capacitance detection circuit in the embodiment of the present application;

[0052] Figure 4 It is a circuit schematic diagram of another specific embodiment of a self-mutual capacitance detection circuit in the embodiment of the present application. DETAILED DESCRIPTION

[0053] The following will clearly and completely describe the concept of the present application and the technical effects produced in combination with the embodiments, so as to fully understand the purpose, features and effects of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of them. Based on the embodiments of the present application, other embodiments obtained by those skilled in the art without creative work are all within the scope of protection of the present application.

[0054] In the description of this application, if it involves a description of orientation, such as "upper", "lower", "front", "back", "left", "right", etc., the orientation or position relationship indicated is based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing this application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application. If a feature is referred to as being "set", "fixed", "connected", or "installed" on another feature, it can be directly set, fixed, or connected to another feature, or it can be indirectly set, fixed, connected, or installed on another feature.

[0055] In the description of the embodiments of the present application, if "several" is involved, it means more than one, if "multiple" is involved, it means more than two, if "greater than", "less than", or "exceeds" is involved, it should be understood as not including the number itself, if "above", "below", or "within" is involved, it should be understood as including the number itself. If "first" or "second" is involved, it should be understood as being used to distinguish technical features, and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0056] Example 1

[0057] Reference Figure 1 , shows a circuit structure block diagram of a specific embodiment of a self-mutual capacitance detection circuit in the embodiment of the present application. Figure 1As shown, the self-mutual capacitance detection circuit of the embodiment of the present application includes: a sensing module, an excitation module and a detection module; the sensing module includes mutual capacitance and self-capacitance; the excitation module is used to generate an excitation signal; the detection module is used to detect mutual capacitance and self-capacitance; the input end of the sensing module is connected to the excitation module, and the output end of the sensing module is connected to the detection module.

[0058] The excitation module generates an excitation signal, and the sensing module receives the excitation signal and generates a sensing signal. The sensing signal includes a mutual capacitance sensing signal and a self-capacitance sensing signal. The detection module processes the received sensing signal and outputs the final signal quantity. The signal quantity output by the detection module is affected by the excitation signal and the sensing signal. The excitation signal is known, and the sensing signal can be calculated by detecting the output signal quantity, thereby realizing the simultaneous detection of the mutual capacitance and self-capacitance of the sensing element.

[0059] In some other embodiments of the present application, the excitation module includes: a first excitation module and a second excitation module; the first excitation module includes a first excitation source and a second excitation source, the first excitation source is connected to the sensing module through a first switch; the second excitation source is connected to the sensing module through a second switch; the second excitation module includes a third excitation source and a fourth excitation source, the third excitation source is connected to the sensing module through a third switch; the fourth excitation source is connected to the sensing module through a fourth switch.

[0060] The excitation module is divided into a first excitation module and a second excitation module so that different excitation signals are applied to the mutual capacitance and self-capacitance of the sensing module respectively. The connection between the excitation source and the sensing module is controlled by a switch, so as to facilitate the control of the input of the excitation signal.

[0061] In some other embodiments of the present application, the sensing module includes: a first transmitting electrode, a second transmitting electrode and a receiving electrode; the first transmitting electrode is coupled to the receiving electrode to form a mutual capacitance; the second transmitting electrode is used to transmit an excitation signal to the conductor, and the conductor is coupled to the receiving electrode to form a self-capacitance; the first transmitting electrode is respectively connected to the first switch and the second switch, the second transmitting electrode is respectively connected to the third switch and the fourth switch, and the receiving electrode is connected to the detection module.

[0062] The sensing module includes mutual capacitance and self capacitance. The mutual capacitance is formed by coupling the first transmitting electrode to the receiving electrode, and the self capacitance is formed by coupling the conductor to the receiving electrode. The first excitation module applies a first excitation signal to the first transmitting electrode, thereby generating a mutual capacitance sensing signal. The second excitation module applies a second excitation signal to the second transmitting electrode, and the second transmitting electrode then transmits the second excitation signal to the adjacent conductor, thereby generating a self-capacitance sensing signal.

[0063] In some other embodiments of the present application, the detection module includes: an operational amplifier, a feedback capacitor and a feedback loop switch; the non-inverting input terminal of the operational amplifier is connected to a reference voltage source, and the reference voltage source is used to provide a reference voltage for the operational amplifier; the inverting input terminal of the operational amplifier is respectively connected to one end of the feedback capacitor, one end of the feedback loop switch and the output end of the sensing module; the other end of the feedback capacitor is connected to the output end of the operational amplifier, and the other end of the feedback loop switch is connected to the output end of the operational amplifier.

[0064] The sensing signal generated by the sensing module is input to the detection module, and the detection module processes the sensing signal. Specifically, the detection module includes an operational amplifier, a feedback capacitor and a feedback loop switch. The sensing signal is input to the inverting input terminal of the operational amplifier. The operational amplifier amplifies the sensing signal and uses the feedback capacitor to bias the operational amplifier, thereby removing the capacitive background noise of the amplified signal and obtaining the final output signal. The feedback capacitor is charged and discharged by controlling the on-off of the feedback loop through the switch to achieve the biasing effect of the feedback capacitor on the operational amplifier. The reference voltage of the operational amplifier can be adjusted according to actual conditions. In other embodiments of the present application, the reference voltage of the operational amplifier is half of the operating voltage.

[0065] In other embodiments of the present application, refer to Figure 2 , shows a circuit structure block diagram of another specific embodiment of a self-mutual capacitance detection circuit in the embodiment of the present application. Figure 2 As shown, the self-mutual capacitance detection circuit of the embodiment of the present application includes: a sensing module, an excitation module, a detection module and an adjustment module; the sensing module includes mutual capacitance and self-capacitance; the excitation module is used to generate an excitation signal; the detection module is used to detect mutual capacitance and self-capacitance; the adjustment module is used to adjust the signal amount output by the sensing module, and the signal amount includes mutual capacitance signal amount and self-capacitance signal amount; the input end of the sensing module is connected to the excitation module, and the output end of the sensing module is respectively connected to the detection module and the adjustment module.

[0066] The excitation module generates an excitation signal, and the sensing module receives the excitation signal and generates a sensing signal. The sensing signal includes a mutual capacitance sensing signal and a self-capacitance sensing signal. The adjustment module receives the sensing signal, adds an adjustment signal on the basis of the sensing signal, and inputs the initially processed signal quantity into the detection module. The detection module reprocesses the received signal quantity and outputs the final signal quantity. The signal quantity output by the detection module is affected by the excitation signal, the sensing signal and the adjustment signal. The excitation signal and the adjustment signal are known. By detecting the output signal quantity, the sensing signal can be calculated, thereby realizing the simultaneous detection of the mutual capacitance and self-capacitance of the sensing element. In addition, adding the adjustment signal to the sensing signal can increase the output range of the signal quantity, thereby improving the applicability of the circuit.

[0067] Example 2

[0068] An embodiment of the present application provides a self-mutual capacitance detection method, which controls the self-mutual capacitance detection circuit of some embodiments of the present application, and the method includes: a reset step and a charge transfer step; the reset step includes: performing reset control on the circuit, calculating the total charge of the circuit, and obtaining a first total charge; the charge transfer step includes: performing charge transfer control on the circuit, calculating the total charge of the circuit, and obtaining a second total charge; according to the charge conservation relationship between the first total charge and the second total charge, the output signal amount of the circuit is obtained.

[0069] Among them, the circuit is reset controlled, including: controlling the input of the excitation signal, closing the feedback loop switch of the operational amplifier, so as to discharge the feedback capacitor of the operational amplifier. The circuit is charge transferred controlled, including: controlling the input of the excitation signal, opening the feedback loop switch of the operational amplifier, so that the charge on the self-capacitance and mutual capacitance of the sensing module is transferred to the feedback capacitor. According to the law of conservation of charge, the first total charge amount before and after the charge transfer is equal to the second total charge amount, so that the output signal amount of the circuit can be calculated.

[0070] In some other embodiments of the present application, the method for controlling the self-mutual capacitance detection circuit of some embodiments of the present application also includes an adjustment step, and the adjustment step includes: adjusting and controlling the circuit to adjust the first total charge amount and the second total charge amount.

[0071] The circuit is regulated and controlled, including: controlling the input of the excitation signal, increasing the regulated signal amount, thereby increasing the regulated signal component in the first total charge amount and the second total charge amount. The regulated signal amount is used to offset the fixed mutual capacitance signal amount and self-capacitance signal amount in the output signal amount, thereby obtaining the relationship between the output signal amount and the mutual capacitance change amount and the self-capacitance change amount, thereby increasing the range of the output signal amount.

[0072] Example 3

[0073] Reference Figure 3 , shows a circuit schematic diagram of a specific embodiment of a self-mutual capacitance detection circuit in the embodiment of the present application. Figure 3As shown, the self-mutual capacitance detection circuit of the embodiment of the present application includes: excitation sources V1, V2, V3 and V4, switches S1, S2, S3 and S4, mutual capacitance C1 and self capacitance C2, operational amplifier OpAmp, reference voltage source V5 of the operational amplifier, inverting input terminal VRX of the operational amplifier, output terminal VO of the operational amplifier, feedback capacitor C3 of the operational amplifier and feedback loop switch S5; the excitation source V1 is connected to one end of the mutual capacitance C1 through the switch S1, the excitation source V2 is connected to one end of the mutual capacitance C1 through the switch S2, and the other end of the mutual capacitance C1 is connected to The inverting input terminal VRX of the operational amplifier; the excitation source V3 is connected to one end of the self-capacitor C2 through the switch S3, the excitation source V4 is connected to one end of the self-capacitor C2 through the switch S4, and the other end of the self-capacitor C2 is connected to the inverting input terminal VRX of the operational amplifier; one end of the feedback capacitor C3 is connected to the inverting input terminal VRX of the operational amplifier, and the other end of the feedback capacitor C3 is connected to the output terminal VO of the operational amplifier; one end of the feedback loop switch S5 is connected to the inverting input terminal VRX of the operational amplifier, and the other end of the feedback loop switch S5 is connected to the output terminal VO of the operational amplifier.

[0074] In some other embodiments of the present application, the self-mutual capacitance detection circuit of the above-mentioned embodiment of the present application is controlled, including a reset step and a charge transfer step.

[0075] Reset steps:

[0076] To reset the circuit, refer to Figure 3 , close the feedback loop switch S5, close switches S1 and S3, keep switches S2 and S4 open, apply excitation voltage VTX1 to mutual capacitance C1 through excitation source V1, apply excitation voltage VTX3 to self capacitance C2 through excitation source V3, and apply reference voltage VCM to operational amplifier OpAmp through reference voltage source V5 of operational amplifier. The capacitance value of mutual capacitance C1 is C M -C TM , where C M is the mutual capacitance between the first transmitting electrode and the receiving electrode, C TM is the change in mutual capacitance C1 of the inductive element caused by the proximity of the conductors. The capacitance value of the self-capacitance C2 is C S +C TS , C S is the self-capacitance value between the second transmitting electrode and the receiving electrode, C TS is the change in the self-capacitance C2 of the inductive element caused by the proximity of the conductor. The capacitance value of the feedback capacitor C3 is C F .

[0077] The voltage of the inverting input terminal VRX of the operational amplifier and the voltage of the output terminal VO of the operational amplifier are both reset to VCM, and the first total charge Q1 of the circuit is as shown in formula (1):

[0078] Q 1 =(VCM-VTX1)·(C M -C TM )+(VCM-VTX3)·(C S +C TS ) (1)

[0079] Charge transfer steps:

[0080] To transfer charge to the circuit, refer to Figure 3 , open the feedback loop switch S5, close switches S2 and S4, open switches S1 and S3, apply an excitation voltage VTX2 to the mutual capacitance C1 through the excitation source V2, apply an excitation voltage VTX4 to the self-capacitance C2 through the excitation source V4, and the reference voltage source V5 of the operational amplifier continues to apply the reference voltage VCM to the operational amplifier OpAmp.

[0081] Due to the virtual short characteristic of the operational amplifier, the voltage at the inverting input terminal VRX of the operational amplifier is clamped to VCM. Assuming that the voltage at the output terminal VO of the operational amplifier is VOUT, the second total charge Q2 of the circuit is as shown in formula (2):

[0082]

[0083] According to the law of conservation of charge, the amount of charge before and after the charge transfer remains unchanged, that is, the first total charge amount Q1 and the second total charge amount Q2 are equal, and the signal amount VOUT output by the operational amplifier is obtained as shown in formula (3):

[0084]

[0085] Due to the change in mutual capacitance C1 TM The change in self-capacitance C2 TS It can reflect the distance of the conductors. From formula (3), we can see that if VTX2>VTX1 and VTX3>VTX4, the change in mutual capacitance C1 is C TM The change in self-capacitance C2 TS They can be superimposed on each other, thereby increasing the signal VOUT output by the operational amplifier and increasing the output signal-to-noise ratio.

[0086] In other embodiments of the present application, by controlling the excitation source, VTX2 and VTX1 are made to have the same frequency and opposite phases, and VTX3 and VTX4 are made to have the same frequency and opposite phases, thereby increasing the signal amount output by the circuit, thereby increasing the signal-to-noise ratio and improving the accuracy of the detection result.

[0087] Reference Figure 4 , shows a circuit schematic diagram of another specific embodiment of a self-mutual capacitance detection circuit in the embodiment of the present application. Figure 4 As shown, the self-mutual capacitance detection circuit of the embodiment of the present application includes: excitation sources V1, V2, V3 and V4, switches S1, S2, S3 and S4, mutual capacitance C1 and self capacitance C2, adjustment excitation sources V5 and V6, adjustment switches S5 and S6, adjustment capacitor C3, operational amplifier OpAmp, reference voltage source V7 of the operational amplifier, inverting input terminal VRX of the operational amplifier, output terminal VO of the operational amplifier, feedback capacitor C4 of the operational amplifier and feedback loop switch S7; the excitation source V1 is connected to one end of the mutual capacitance C1 through the switch S1, the excitation source V2 is connected to one end of the mutual capacitance C1 through the switch S2, and the other end of the mutual capacitance C1 is connected to the inverting input terminal VRX of the operational amplifier; the excitation source V3 is connected to To one end of the self-capacitor C2, the excitation source V4 is connected to one end of the self-capacitor C2 through the switch S4, and the other end of the self-capacitor C2 is connected to the inverting input terminal VRX of the operational amplifier; the regulating excitation source V5 is connected to one end of the regulating capacitor C3 through the regulating switch S5, the regulating excitation source V6 is connected to one end of the regulating capacitor C3 through the regulating switch S6, and the other end of the regulating capacitor C3 is connected to the inverting input terminal VRX of the operational amplifier; one end of the feedback capacitor C4 is connected to the inverting input terminal VRX of the operational amplifier, and the other end of the feedback capacitor C4 is connected to the output terminal VO of the operational amplifier; one end of the feedback loop switch S7 is connected to the inverting input terminal VRX of the operational amplifier, and the other end of the feedback loop switch S7 is connected to the output terminal VO of the operational amplifier.

[0088] In some other embodiments of the present application, the self-mutual capacitance detection circuit of the above-mentioned embodiment of the present application is controlled, including a reset step, a charge transfer step and an adjustment step.

[0089] Reset steps and adjustment steps:

[0090] Reset and adjust the circuit, refer to Figure 4 , close the feedback loop switch S7, close switches S1, S3 and S5, keep switches S2, S4 and S6 open, apply excitation voltage VTX1 to mutual capacitance C1 through excitation source V1, apply excitation voltage VTX3 to self capacitance C2 through excitation source V3, apply adjustment voltage VB1 to adjustment capacitance C3 through adjustment excitation source V5, and apply reference voltage VCM to operational amplifier OpAmp through reference voltage source V7 of operational amplifier. The capacitance value of mutual capacitance C1 is C M -C TM , where C M is the mutual capacitance between the first transmitting electrode and the receiving electrode, C TMis the change in mutual capacitance C1 of the inductive element caused by the proximity of the conductors. The capacitance value of the self-capacitance C2 is C S +C TS , C S is the self-capacitance value between the second transmitting electrode and the receiving electrode, C TS is the change in the self-capacitance C2 of the inductive element caused by the proximity of the conductor. The capacitance value of the adjustment capacitor C3 is C B , the capacitance value of feedback capacitor C4 is C F .

[0091] The voltage of the inverting input terminal VRX of the operational amplifier and the voltage of the output terminal VO of the operational amplifier are both reset to VCM, and the first total charge Q1 of the circuit is as shown in formula (4):

[0092]

[0093] Charge transfer step and conditioning step:

[0094] Charge transfer and regulation of the circuit, refer to Figure 4 , open the feedback loop switch S7, close switches S2, S4 and S6, open switches S1, S3 and S5, apply an excitation voltage VTX2 to the mutual capacitance C1 through the excitation source V2, apply an excitation voltage VTX4 to the self-capacitance C2 through the excitation source V4, apply an adjustment voltage VB2 to the adjustment capacitor C3 through the adjustment excitation source V6, and the reference voltage source V7 of the operational amplifier continues to apply the reference voltage VCM to the operational amplifier OpAmp.

[0095] Due to the virtual short characteristic of the operational amplifier, the voltage at the inverting input terminal VRX of the operational amplifier is clamped to VCM. Assuming that the voltage at the output terminal VO of the operational amplifier is VOUT, the second total charge Q2 of the circuit is as shown in formula (5):

[0096]

[0097] According to the law of conservation of charge, the amount of charge before and after the charge transfer remains unchanged, that is, the first total charge amount Q1 and the second total charge amount Q2 are equal, and the signal amount VOUT output by the operational amplifier is obtained as shown in formula (6):

[0098]

[0099] Due to the change in mutual capacitance C1 TM The change in self-capacitance C2 TS It can reflect the distance of the conductors. From formula (6), we can see that if VTX2>VTX1 and VTX3>VTX4, the change in mutual capacitance C1 is TM The change in self-capacitance C2 TScan be superimposed on each other, thereby increasing the signal VOUT output by the operational amplifier and increasing the output signal-to-noise ratio. However, the signal VOUT output by the operational amplifier also includes a fixed mutual capacitance signal C M and the self-capacitance signal C S , resulting in a reduction in the output range of the signal VOUT. Therefore, by adjusting C B , or, by adjusting VB1 or VB2 so that the adjusted signal and the fixed signal cancel each other out, the output range of the signal VOUT can be increased. Finally, the signal VOUT output by the operational amplifier is as shown in formula (7):

[0100]

[0101] Example 4

[0102] An embodiment of the present application provides a chip, including the self-mutual capacitance detection circuit of some embodiments of the present application.

[0103] The chip of the embodiment of the present application can simultaneously detect the self-capacitance and mutual capacitance of the sensing element, thereby increasing the signal amount output by the circuit, thereby increasing the signal-to-noise ratio and improving the accuracy of the detection result.

[0104] Example 5

[0105] An embodiment of the present application provides a device, including at least one processor, and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor can: execute the self-mutual capacitance detection method of some embodiments of the present application.

[0106] The device of the embodiment of the present application can simultaneously detect the self-capacitance and mutual capacitance of the sensing element, thereby increasing the signal amount output by the circuit, thereby increasing the signal-to-noise ratio and improving the accuracy of the detection result.

[0107] In a device of an embodiment of the present application, the processor may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or any conventional processor, etc. The processor is the control center of an executable device of a self-mutual capacitance detection method, and various interfaces and lines are used to connect the various parts of the entire executable device of a self-mutual capacitance detection method.

[0108] The memory can be used to store computer programs and / or modules, and the processor realizes various functions of an executable device of a self-mutual capacitance detection method by running or executing the computer programs and / or modules stored in the memory, and calling the data stored in the memory. The memory may mainly include a program storage area and a data storage area, wherein the program storage area may store an operating system, an application required for at least one function (such as a sound playback function, an image playback function, etc.), etc.; the data storage area may store data created according to the use of the mobile phone (such as audio data, a phone book, etc.), etc. In addition, the memory may include a high-speed random access memory, and may also include a non-volatile memory, such as a hard disk, a memory, a plug-in hard disk, a smart memory card (Smart Media Card, SMC), a secure digital (SecureDigital, SD) card, a flash card (Flash Card), at least one disk storage device, a flash memory device, or other volatile solid-state storage devices.

[0109] The embodiments of the present application are described in detail above in conjunction with the accompanying drawings, but the present application is not limited to the above embodiments. Various changes can be made within the knowledge of ordinary technicians in the relevant technical field without departing from the purpose of the present application. In addition, the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

Claims

1. A self-mutual capacitance detection circuit, It is characterized in that The circuit comprises: a sensing module, an excitation module and a detection module; The sensing module includes mutual capacitance and self capacitance; The excitation module is used to generate an excitation signal, and the excitation module includes: a first excitation module and a second excitation module; the first excitation module includes a first excitation source and a second excitation source, the first excitation source is connected to the sensing module through a first switch; the second excitation source is connected to the sensing module through a second switch; the second excitation module includes a third excitation source and a fourth excitation source, the third excitation source is connected to the sensing module through a third switch; the fourth excitation source is connected to the sensing module through a fourth switch; The detection module is used to detect the mutual capacitance and the self-capacitance; the detection module includes: an operational amplifier, a feedback capacitor and a feedback loop switch; the non-inverting input terminal of the operational amplifier is connected to a reference voltage source, and the reference voltage source is used to provide a reference voltage for the operational amplifier; the inverting input terminal of the operational amplifier is respectively connected to one end of the feedback capacitor, one end of the feedback loop switch and the output end of the sensing module; the other end of the feedback capacitor is connected to the output end of the operational amplifier, and the other end of the feedback loop switch is connected to the output end of the operational amplifier; The input end of the sensing module is connected to the excitation module, and the output end of the sensing module is connected to the detection module; the sensing module includes: a first transmitting electrode, a second transmitting electrode and a receiving electrode; the first transmitting electrode is coupled to the receiving electrode to form a mutual capacitance; the second transmitting electrode is used to transmit an excitation signal to a conductor, and the conductor is coupled to the receiving electrode, so that the second transmitting electrode and the receiving electrode are coupled to form a self-capacitance; the first transmitting electrode is respectively connected to the first switch and the second switch, the second transmitting electrode is respectively connected to the third switch and the fourth switch, and the receiving electrode is connected to the detection module, the first excitation module applies a first excitation signal to the first transmitting electrode to generate a mutual capacitance sensing signal, and the second excitation module applies a second excitation signal to the second transmitting electrode, so that the second transmitting electrode transmits the second excitation signal to the adjacent conductor to generate a self-capacitance sensing signal; The circuit further includes a regulating module, which is used to regulate the signal quantity output by the sensing module, wherein the signal quantity includes a mutual capacitance signal quantity and a self-capacitance signal quantity; the regulating module is connected to the output end of the sensing module; The sensing module generates a sensing signal according to the received excitation signal, the adjustment module receives the sensing signal, adds an adjustment signal on the basis of the sensing signal, and inputs the initially processed signal quantity into the detection module, the detection module reprocesses the received signal quantity, and outputs the final signal quantity to realize the simultaneous detection of the mutual capacitance and self-capacitance of the sensing element.

2. The self-mutual capacitance detection circuit according to claim 1, It is characterized in that The adjustment module includes: an adjustable capacitor, a first adjustable excitation source and a second adjustable excitation source; The first adjustable excitation source is connected to one end of the adjustable capacitor via a first adjustment switch; The second adjustable excitation source is connected to one end of the adjustable capacitor via a second adjustment switch; The other end of the adjustable capacitor is connected to the output end of the sensing module.

3. A self-mutual capacitance detection method, It is characterized in that The method is used for the self-mutual capacitance detection circuit according to any one of claims 1 to 2, and the method comprises: a reset step and a charge transfer step; The resetting step includes: performing reset control on the circuit, calculating the total charge of the circuit, and obtaining a first total charge; wherein, performing reset control on the circuit includes: closing the feedback loop switch, closing the first switch and the third switch, keeping the second switch and the fourth switch open, applying an excitation voltage VTX1 to the mutual capacitance through the first excitation source, applying an excitation voltage VTX3 to the self-capacitance through the third excitation source, applying a reference voltage VCM to the operational amplifier through the reference voltage source of the operational amplifier, and the capacitance value of the mutual capacitance is C M -C TM , where C M is the mutual capacitance between the first transmitting electrode and the receiving electrode, C TM is the change in mutual capacitance of the inductive element caused by the proximity of the conductors, and the capacitance value of the self-capacitance is C S +C TS , C S is the self-capacitance value between the second transmitting electrode and the receiving electrode, C TS is the change in the self-capacitance of the inductive element caused by the proximity of the conductor, the voltage at the inverting input terminal of the operational amplifier and the voltage at the output terminal of the operational amplifier are both reset to VCM, and the calculation formula of the first total charge Q1 of the circuit is: Q1=(VCM-VTX1)·(C M -C TM )+(VCM-VTX3)·(C S +C TS ) The charge transfer step includes: performing charge transfer control on the circuit, calculating the total charge amount of the circuit, and obtaining a second total charge amount; the charge transfer control on the circuit includes: disconnecting the feedback loop switch, closing the second switch and the fourth switch, disconnecting the first switch and the third switch, applying an excitation voltage VTX2 to the mutual capacitance through the second excitation source, applying an excitation voltage VTX4 to the self-capacitance through the fourth excitation source, and the reference voltage source of the operational amplifier continues to apply the reference voltage VCM to the operational amplifier, then the voltage of the inverting input terminal VRX of the operational amplifier is VCM, when the voltage of the output terminal of the operational amplifier is VOUT, the capacitance value of the feedback capacitor is C F , the calculation formula of the second total charge Q2 of the circuit is: Q2=(VCM-VTX2)·(C M -C TM )+(VCM-VTX4)·(C S +C TS )+(VCM-VOUT)·C F According to the charge conservation relationship between the first total charge amount and the second total charge amount, the output signal amount of the circuit is obtained, and the calculation formula of the output signal VOUT is: 。 4. The self-mutual capacitance detection method according to claim 3, It is characterized in that The method further includes an adjustment step, wherein the adjustment step includes: performing adjustment control on the circuit to adjust the first total charge amount and the second total charge amount.

5. A chip, It is characterized in that The chip comprises the self-mutual capacitance detection circuit as claimed in any one of claims 1 to 2.

6. A device, It is characterized in that The device comprises at least one processor, and a memory communicatively connected to at least one of the processors; wherein, The memory stores instructions executable by at least one of the processors, the instructions being executed by at least one of the processors to enable at least one of the processors to: Execute the self-mutual capacitance detection method as described in any one of claims 3 to 4.

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