CN118068988A - Self-capacitance touch detection circuit and detection method - Google Patents
Self-capacitance touch detection circuit and detection method Download PDFInfo
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- CN118068988A CN118068988A CN202410501443.2A CN202410501443A CN118068988A CN 118068988 A CN118068988 A CN 118068988A CN 202410501443 A CN202410501443 A CN 202410501443A CN 118068988 A CN118068988 A CN 118068988A
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
- H03K17/94—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the way in which the control signals are generated
- H03K17/96—Touch switches
- H03K17/962—Capacitive touch switches
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
- G06F3/01—Input arrangements or combined input and output arrangements for interaction between user and computer
- G06F3/03—Arrangements for converting the position or the displacement of a member into a coded form
- G06F3/041—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
- G06F3/0416—Control or interface arrangements specially adapted for digitisers
- G06F3/0418—Control or interface arrangements specially adapted for digitisers for error correction or compensation, e.g. based on parallax, calibration or alignment
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
- G06F3/01—Input arrangements or combined input and output arrangements for interaction between user and computer
- G06F3/03—Arrangements for converting the position or the displacement of a member into a coded form
- G06F3/041—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
- G06F3/044—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means by capacitive means
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- H—ELECTRICITY
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- H03F—AMPLIFIERS
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- H03F3/70—Charge amplifiers
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Abstract
The invention discloses a self-capacitance touch detection circuit and a detection method, wherein the switching of a first switch and a second switch is controlled in different stages of excitation voltage, the voltage on an induction electrode is changed, the change of the charge on the induction electrode is obtained, and a detection signal is output to a signal analysis system according to the change of the charge; and after the sum of the detection signals is input into the signal analysis system for analysis and processing, comparing the sum with a threshold signal, and judging whether touch occurs or not according to a comparison result. Through topological relation and switch time sequence control between components and parts, the size of the self-capacitance touch detection signal is improved, and then the time of self-capacitance touch detection is shortened, the sensitivity of the self-capacitance detection is improved, and the circuit structure is simple, the detection signal is improved without additionally adding a boost power supply module, and the self-capacitance touch detection circuit is easy to prepare.
Description
Technical Field
The invention belongs to the technical field of touch signal detection, and particularly relates to a self-capacitance touch detection circuit and a detection method.
Background
The touch sensor is an important man-machine interaction mode because of its simple, direct and humanized design. Capacitive touch sensing has become a mainstream technology in electronic products such as mobile phones, tablets, wearable devices and the like, and compared with resistive touch, infrared touch and ultrasonic touch, capacitive touch has obvious advantages in the aspects of durability, multi-finger, portability and the like. The sensitivity, the accuracy and the anti-interference performance of touch detection have great influence on human-computer interaction experience.
The capacitive touch sensor receives the electrode and has the electric capacity with ground (self capacitance) or with transmission electrode (mutual capacitance), the finger is close to the sensor and causes this electric capacity value to change, the touch chip detects the electric capacity change, and convey the detection signal to the host computer and realize the judgement to movements such as touch position, orbit and gesture.
Fig. 1 is a schematic diagram of a conventional self-capacitance detection circuit, and when a finger approaches or touches a capacitive screen, the corresponding operation process of the detection capacitance can be simply described as follows: one port of the capacitor 101 is grounded, the other port is coupled to the inverting input end of the charge amplifier 103 through the electrode 102, and the non-inverting input end of the charge amplifier 103 is connected with an excitation voltage; the electrode 102 is coupled to the output end of the charge amplifier 103 through the integrating capacitor 104 to form a load path; the charge amplifier 103 has a non-inverting input terminal as an output terminal, and a voltage periodically changing between VH (peak voltage of the excitation voltage) and VL (valley voltage of the excitation voltage) is applied. When a touch occurs, assuming that the capacitance 101 changes by Δc, the output voltage of the charge amplifier 103 will change by Δv=Δc× (VH-VL)/Cint, which is the capacitance value of the integrating capacitance 104, and it is apparent that the output voltage is proportional to the magnitude of the touch capacitance, so it can be determined whether or not a touch occurs by measuring the magnitude of Δv.
To improve the detection of self-capacitance, various approaches have been tried in the prior art to improve the self-capacitance signal, for example: decrease Cint, increase VH or decrease VL. In fact, many approaches are impractical or costly due to various limitations, such as reducing Cint, where the touch detection range is reduced and noise is increased, while increasing VH or VL causes the charge amplifier 103 to operate non-linearly, introducing new problems or even causing the chip to not function properly, increasing Δc is more a requirement to change the process structure, and is costly.
Disclosure of Invention
The invention provides a self-capacitance touch detection circuit and a self-capacitance touch detection method, which are simple in circuit structure and easy to realize, and the self-capacitance touch detection signal, the sensitivity of the self-capacitance touch detection and the detection efficiency are improved.
The present invention provides a self-capacitance touch detection circuit, comprising: the device comprises a first switch, a second switch, a third switch, a charge transfer device, an induction electrode, a screen channel capacitor and a signal analysis system;
the screen channel capacitor is connected with the induction electrode, the induction electrode is connected with the first input end of the charge transfer device through the first switch, the second input end of the charge transfer device is connected with the excitation voltage, one end of the second switch is connected between the induction electrode and the first switch, and the other end of the second switch is connected with the reference voltage;
One end of the third switch is connected with the first switch, the second switch and the induction electrode, and the other end of the third switch is grounded;
controlling the opening and closing of the first switch, the second switch and the third switch in different phases of the excitation voltage, and changing the voltage on the induction electrode so as to obtain the change amount of the charge on the induction electrode, wherein the charge transfer device outputs a detection signal to the signal analysis system according to the change amount of the charge;
And after the sum of the detection signals is input to the signal analysis system for analysis and processing, comparing the sum with a threshold signal, and judging whether touch occurs or not according to a comparison result.
Further, the charge transfer device comprises a charge transporter or a charge amplifier.
Further, a first input terminal of the charge transmitter is coupled to a first output terminal of the charge transmitter, and a second output terminal of the charge transmitter is coupled to the signal analysis system.
Further, the signal analysis system comprises a current-to-voltage module, an analog-to-digital converter and a processor;
The current-to-voltage module is used for converting a current signal into a voltage signal;
the analog-to-digital converter is used for converting the voltage signal into a digital signal;
the processor is used for processing the digital signal, comparing the digital signal with a threshold signal and judging whether touch occurs or not according to a comparison result.
The invention also provides a self-capacitance touch detection method, which adopts the self-capacitance touch detection circuit, and comprises the following steps:
When the excitation voltage jumps for the first time, the first switch is closed, the second switch is opened, and the charge transfer device drives the voltage on the induction electrode to rise to a first voltage to obtain a first charge variation;
After the first voltage on the induction electrode is kept stable, the first switch is opened, the second switch is closed, and the induction electrode is charged to the first voltage;
when the excitation voltage jumps for the second time, the first switch is closed, the second switch is opened, and the charge transfer device drives the induction electrode to drop from the second voltage to the third voltage to obtain a second charge variation;
after the third voltage on the induction electrode is kept stable, the first switch and the second switch are opened, the third switch is closed, and the induction electrode discharges to a fourth voltage;
The charge transfer device outputs a detection signal according to the sum of the first charge variation and the second charge variation, the sum of a plurality of detection signals is input into the signal analysis system for analysis and processing, and then the detection signal is compared with a threshold signal, and whether touch occurs is judged according to a comparison result.
Further, the first jump is that the excitation voltage jumps from high level to low level, and the second jump is that the excitation voltage jumps from low level to high level.
Further, after the third voltage on the induction electrode is kept stable, the first switch and the second switch are opened, the third switch is closed, and the induction electrode discharges to the fourth voltage.
Further, the second voltage is higher than the first voltage, and the fourth voltage is lower than the third voltage.
Further, the first voltage is a peak voltage of the excitation voltage, the second voltage is a power supply voltage, the third voltage is a valley voltage of the excitation voltage, and the fourth voltage is a ground voltage.
Further, the first charge variation is cxx (VH-0), where Cx is an equivalent capacitance on the first electrode and VH is a peak voltage of the excitation voltage. The second varying charge amount is cxx (VDD-VL), where VDD is a power supply voltage and VL is a valley voltage of the excitation voltage.
Compared with the prior art, the invention has at least the following technical effects:
The invention changes the voltage on the induction electrode by controlling the opening and closing of the first switch, the second switch and the third switch in different phases of excitation voltage, obtains the change amount of the charge on the induction electrode, and outputs a detection signal to the signal analysis system according to the change amount of the charge; and after the sum of the detection signals is input to the signal analysis system for analysis and processing, comparing the sum with a threshold signal, and judging whether touch occurs or not according to a comparison result. Through topological relation and switch time sequence control between components and parts, the size of the self-capacitance touch detection signal is improved, the time of self-capacitance touch detection is shortened, the sensitivity of the self-capacitance detection is improved, the circuit structure is simple, a boosting power supply module is not required to be additionally arranged to improve the detection signal, and the self-capacitance touch detection circuit is easy to prepare.
Drawings
FIG. 1 is a schematic diagram of a circuit structure of a self-capacitance touch detection circuit in the prior art;
fig. 2 is a schematic circuit diagram of a self-capacitive touch detection circuit according to a first embodiment of the present invention;
Fig. 3 is a schematic circuit diagram of another self-capacitive touch detection circuit according to the first embodiment of the present invention;
Fig. 4 is a timing control diagram in the first embodiment.
Detailed Description
In the following, a self-capacitive touch detection circuit and detection method of the present invention will be described in conjunction with the schematic drawings, in which preferred embodiments of the present invention are shown, it being understood that one skilled in the art can modify the invention described herein while still achieving the advantageous effects of the invention. Accordingly, the following description is to be construed as broadly known to those skilled in the art and not as limiting the invention.
The invention is more particularly described by way of example in the following paragraphs with reference to the drawings. The advantages and features of the present invention will become more apparent from the following description. It should be noted that the drawings are in a very simplified form and are all to a non-precise scale, merely for purposes of facilitating and clearly aiding in the description of embodiments of the invention.
Example 1
Referring to fig. 2 and 3, the present embodiment provides a self-capacitance touch detection circuit, which includes a first switch S1, a second switch S2, a charge transfer device, an inductive electrode 1, a screen channel capacitor C1 and a signal analysis system.
Specifically, the screen channel capacitor C1 is connected to the sensing electrode 1, the sensing electrode 1 is connected to the first input end of the charge transfer device through the first switch S1, the second input end of the charge transfer device is connected to the excitation voltage VCM, one end of the second switch S2 is connected between the sensing electrode 1 and the first switch S1, and the other end is connected to the reference voltage. One end of the third switch S3 is connected to the first switch S1, the second switch S2, and the sensing electrode 1, and the other end is grounded. In a specific example, referring to fig. 4, the first switch S1 and the second switch S2 are controlled by a third pulse signal PH3 and a first pulse signal PH1, respectively, and by controlling the duty ratio of the pulse signals, the switches are kept in a closed state at a high level, and kept in an open state at a low level, so as to realize voltage control on the first electrode.
In this example, the charge transfer device is a charge transporter 214 or a charge amplifier 218.
The principle of operation of the self-capacitance touch detection circuit will be described below using the charge transporter 214 as an example:
When a charge transporter 214 is used as the charge transfer device, a first input of the charge transporter 214 is coupled to a first output of the charge transporter 214, and a second output of the charge transporter 214 is coupled to the signal analysis system. In a specific example, the first input is an inverting input and the second input is a non-inverting input. The specific driving principle is as follows: when the excitation voltage VCM at the non-inverting input of the charge transmitter 214 changes, the inverting input is coupled to the first output, so that the inverting input follows the non-inverting input, so as to control and drive the self-capacitance channel connected to the sensing electrode 1, and the magnitude of the current output from the second output of the charge transmitter 214 to the signal analysis system is proportional to the absolute value of the magnitude of the current output from the first output of the charge transmitter 214, i.e. iout=k×iout0, K is a configurable and adjustable constant.
The control process of the self-capacitance touch detection circuit is as follows: in different phases of the excitation voltage VCM, the first switch S1 and the second switch S2 are controlled to be turned on or off, so as to change the voltage on the sensing electrode 1, thereby obtaining the change amount of the charge on the sensing electrode 1, and the charge transmitter 214 outputs a detection current Iout to the signal analysis system according to the change amount of the charge. It can be understood that, in this example, the magnitude of the current at the first output end of the charge transmitter 214 is related to the change of the charge on the sensing electrode 1, and the change of the charge on the sensing electrode 1 is mainly affected by the change of the capacitance value of the screen channel capacitance C1 when the touch occurs, and in combination with the working principle of the charge transmitter 214, it can be obtained that the magnitude of the detection current Iout output by the charge transmitter 214 is proportional to the absolute value of the magnitude of the current at the first output end, that is, the magnitude of the detection current Iout can represent the magnitude of the capacitance of the screen channel capacitance C1.
The specific control process is as follows:
And S (1), when the excitation voltage VCM jumps for the first time, the first switch S1 is closed, the second switch S2 is opened, and the charge transmitter 214 controls the induction electrode 1 to rise to the first voltage along with the excitation voltage VCM, so that a first charge variation is obtained.
S (2) after the first voltage on the induction electrode 1 is kept stable, opening the first switch S1, closing the second switch S2, and charging the induction electrode 1 to a second voltage;
And S (3) when the excitation voltage VCM jumps for the second time, the first switch S1 is closed, the second switch S2 is opened, and the charge transmitter 214 drives the induction electrode to drop from the second voltage to the third voltage, so that a second charge variation is obtained.
And S (4) the charge transfer device outputs a detection signal according to the sum of the first charge variation and the second charge variation, the sum of a plurality of detection signals is input into the signal analysis system for analysis and processing, and then the detection signal is compared with a threshold signal, and whether touch occurs or not is judged according to a comparison result.
In the actual operation process, the steps S (1) -S (3) are repeatedly executed by continuously playing the excitation voltage VCM, so that a plurality of detection signals can be obtained, and when self capacitance is changed due to touch during self capacitance touch detection, the detection signals are overlapped through repeated accumulation, so that a larger detection signal is obtained, and the signal to noise ratio is improved; if only a small touch signal is needed to judge whether touch occurs, the number of signal detection cycles can be correspondingly reduced according to the size of a specific touch signal, so that the detection time is shortened, and the detection instantaneity is better; when the self capacitance changed by touch becomes smaller, the detection cycle number can be correspondingly increased, so that smaller touch signals are detected, and the detection sensitivity is improved.
The charge transmitter 214 outputs a detection current Iout according to the sum of the first charge variation and the second charge variation, and the detection current Iout is input to a signal analysis system for analysis and processing, so as to obtain a detection signal, and the detection signal is compared with a threshold signal, and whether a touch occurs is determined according to the comparison result.
Further, the induction device further comprises a third switch S3, one end of the third switch S3 is connected with the first switch S1, the second switch S2 and the induction electrode 1, and the other end is grounded. By controlling the third switch S3, the discharge of the sensing electrode 1 is realized, and the specific control steps are as follows:
S (5): after the third voltage on the induction electrode 1 is kept stable, the first switch S1 and the second switch S2 are opened, the third switch S3 is closed, and the induction electrode 1 discharges.
In a specific example, the sensing electrode 1 discharges to a fourth voltage, which may be 0V.
And (3) repeating the steps S (1) -S (3) and S (5), and controlling the voltage swing on the induction electrode 1 to stably swing from the fourth voltage to the first voltage and then swing from the second voltage to the third voltage in each period of the excitation voltage VCM, so as to obtain a relatively stable charge variation.
The third switch S3 is controlled by the second pulse PH2, please refer to fig. 4, in steps S (1) -S (3), the second pulse signal is at low level, the third switch is turned off in the whole course, and in step S (5), the third switch S3 is turned on.
Further, when a charge transporter 214 is used as the charge transfer device, the signal analysis system includes a current-to-voltage module 215, an analog-to-digital converter 216, and a processor 217.
The current-to-voltage module 215 is configured to convert a current signal output by the charge transfer device into a voltage signal. The analog-to-digital converter 216 is configured to convert the voltage signal into a digital signal, and input the digital signal to the processor 217, where the processor 217 processes the digital signal, for example: and carrying out power amplification on the digital signal, and comparing the digital signal of the processing number with a threshold signal, so as to judge whether touch occurs or not according to a comparison result.
In another specific example, referring to fig. 3, when the charge amplifier 218 is used as the charge transfer device, the capacitor in the charge amplifier 218 stores the charge, the control method in steps S1-S4 is also adopted and repeated, the charge amplifier 218 obtains a voltage signal according to the sum of the charge variation amounts as a detection signal, and amplifies the voltage signal, the detection signal is input to the analog-to-digital converter 216 for analog-to-digital conversion, the digital signal is input to the processor 217, the processor 217 processes the digital signal, and the processed digital signal is compared with the threshold signal, so as to determine whether the touch occurs according to the comparison result.
It will be appreciated that the threshold signal needs to be set according to the specific situation, for example, 2050, and the digital signal exceeds the threshold signal to determine that a touch occurs.
Preferably, the circuit further includes n adjacent channel capacitors C3, each adjacent channel capacitor C3 is connected to one sensing electrode 1, each sensing electrode 1 is connected to each other through a mutual capacitor C2, and when a finger touches any screen channel capacitor C1, the capacitance value of the adjacent channel capacitor C3 is also changed, so that the circuit can more accurately detect the position of the finger.
In summary, the invention realizes different voltage changes on the induction electrode 1 by optimizing the self-capacitance detection circuit and controlling the time sequence, does not need to additionally increase a boosting power supply module to improve detection signals and does not need to increase the driving capability of the circuit, has simple circuit structure and easy preparation, and simultaneously ensures the reliability and the practicability of the circuit.
Example two
The present embodiment provides a self-capacitance touch detection method, which adopts the self-capacitance touch detection circuit in the first embodiment, and the method includes:
SI. when the excitation voltage VCM jumps for the first time, closing the first switch S1, opening the second switch S2, and driving the induction electrode 1 by the charge transfer device to reach a first voltage to obtain a first charge variation;
Sii. after the first voltage on the induction electrode 1 remains stable, opening the first switch S1, closing the second switch S2, and charging the induction electrode to a second voltage;
SIII when the exciting voltage VCM jumps for the second time, the first switch S1 is closed, the second switch S2 is opened, and the charge transfer device drives the induction electrode 1 to drop from the second voltage to the third voltage to obtain a second charge variation;
And SIV. The charge transfer device outputs a detection signal according to the sum of the first charge variation and the second charge variation, and the detection signals are input into the signal analysis system for analysis and processing, and then the detection signal is compared with a threshold signal, and whether touch occurs is judged according to the comparison result.
The SI-SIII steps are repeatedly executed through the turn-off and turn-on of the time sequence control switch and the play of the excitation voltage VCM, so that a plurality of detection signals can be obtained, when self capacitance is changed due to touch during self capacitance touch detection, the detection signals are overlapped through repeated accumulation, a larger detection signal is obtained, and the signal to noise ratio is improved; if only a small touch signal is needed to judge whether touch occurs, the number of signal detection cycles can be correspondingly reduced according to the size of a specific touch signal, so that the detection time is shortened, and the detection instantaneity is better; when the self capacitance changed by touch becomes smaller, the detection cycle number can be correspondingly increased, so that smaller touch signals are detected, and the detection sensitivity is improved.
Further, the present embodiment further includes a step SV, where the step SV is set between the step SIII and the step SIV, specifically as follows: after the third voltage on the induction electrode 1 is kept stable, the first switch S1 and the second switch S2 are opened, the third switch S3 is closed, the induction electrode 1 discharges to the fourth voltage, and in the SI-SIII step, the third switch S3 is opened in the whole course.
When the exciting voltage VCM jumps again, the first switch S1 is closed, the second switch S2 and the third switch S3 are opened, and the charge transfer device drives the induction electrode 1 to rise from the fourth voltage to the first voltage, so that the charge variation is obtained again. And by analogy, repeating the steps in S1-SIII and SV in a plurality of playing periods of the excitation voltage VCM, and then executing the SIV step to obtain a plurality of stable charge variation total amounts.
In the prior art, the output voltage change amount Δv=Δc× (VH-VL)/Cint, the voltage swing is VH to VL,
In a specific example, referring to fig. 4, the fourth voltage is a ground voltage (0V), the first voltage is a peak voltage VH of the excitation voltage VCM, the second voltage is a power voltage VDD, and the third voltage is a valley voltage VL of the excitation voltage VCM. At this time, in one period of the excitation voltage VCM, the voltage on the sensing electrode 1 is controlled to rise from 0V to VH, and the first charge variation amount is cxx (VH-0), where Cx is the equivalent capacitance on the first electrode, that is, the capacitance value of the screen channel capacitance. The second charge variation amount is cxx (VDD-VL), that is, the total amount of charge transferred by the charge transfer means is cxx (VH-0) +cxx (VDD-VL) in one period of the pumping voltage VCM playback. It can be seen that the voltage swings from 0V to VH and then from VDD to VL, the voltage swing increases, and the amount of voltage change is improved, thereby improving the sensitivity of touch detection.
It is understood that the peak voltage, the valley voltage, and the power supply voltage of the excitation voltage VCM can be set by those skilled in the art according to the actual situation.
It will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention also include such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.
Claims (9)
1. A self-capacitance touch detection circuit, comprising: the device comprises a first switch, a second switch, a third switch, a charge transfer device, an induction electrode, a screen channel capacitor and a signal analysis system;
The screen channel capacitor is connected with the induction electrode, the induction electrode is connected with the first input end of the charge transfer device through the first switch, the second input end of the charge transfer device is connected with the excitation voltage, one end of the second switch is connected between the induction electrode and the first switch, and the other end of the second switch is connected with the reference voltage; one end of the third switch is connected with the first switch, the second switch and the induction electrode, and the other end of the third switch is grounded;
controlling the opening and closing of the first switch, the second switch and the third switch in different phases of the excitation voltage, and changing the voltage on the induction electrode so as to obtain the change amount of the charge on the induction electrode, wherein the charge transfer device outputs a detection signal to the signal analysis system according to the change amount of the charge;
And after the sum of the detection signals is input to the signal analysis system for analysis and processing, comparing the sum with a threshold signal, and judging whether touch occurs or not according to a comparison result.
2. The self-capacitance touch detection circuit of claim 1, wherein the charge transfer means comprises a charge transmitter or a charge amplifier.
3. The self-capacitance touch detection circuit of claim 2, wherein a first input of the charge transmitter is coupled to a first output of the charge transmitter, and a second output of the charge transmitter is coupled to the signal analysis system.
4. The self-capacitance touch detection circuit of claim 2, wherein the signal analysis system comprises a current-to-voltage module, an analog-to-digital converter, and a processor;
The current-to-voltage module is used for converting a current signal into a voltage signal;
the analog-to-digital converter is used for converting the voltage signal into a digital signal;
the processor is used for processing the digital signal, comparing the digital signal with a threshold signal and judging whether touch occurs or not according to a comparison result.
5. A self-capacitance touch detection method employing the self-capacitance touch detection circuit according to any one of claims 1 to 4, the method comprising:
When the excitation voltage jumps for the first time, the first switch is closed, the second switch and the third switch are opened, and the charge transfer device drives the voltage on the induction electrode to rise to a first voltage to obtain a first charge variation;
After the first voltage on the induction electrode is kept stable, the first switch is opened, the second switch is closed, and the induction electrode is charged to a second voltage;
when the excitation voltage jumps for the second time, the first switch is closed, the second switch and the third switch are opened, and the charge transfer device drives the induction electrode to drop from the second voltage to the third voltage to obtain a second charge variation;
after the third voltage on the induction electrode is kept stable, the first switch and the second switch are opened, the third switch is closed, and the induction electrode discharges to a fourth voltage;
The charge transfer device outputs a detection signal according to the sum of the first charge variation and the second charge variation, the sum of a plurality of detection signals is input into the signal analysis system for analysis and processing, and then the detection signal is compared with a threshold signal, and whether touch occurs is judged according to a comparison result.
6. The self-capacitance touch detection method of claim 5, wherein the first transition is a transition of the stimulus voltage from high to low, and the second transition is a transition of the stimulus voltage from low to high.
7. The self-capacitive touch detection method of claim 5, wherein the second voltage is higher than the first voltage and the fourth voltage is lower than the third voltage.
8. The self-capacitive touch detection method of claim 5, wherein the first voltage is a peak voltage of the excitation voltage, the second voltage is a power supply voltage, the third voltage is a valley voltage of the excitation voltage, and the fourth voltage is a ground voltage.
9. The self-capacitance touch detection method according to claim 8, wherein the first charge variation amount is cxx (VH-0), where Cx is an equivalent capacitance on the first electrode, and VH is a peak voltage of the excitation voltage; the second charge variation is cxx (VDD-VL), where VDD is a power supply voltage and VL is a valley voltage of the excitation voltage.
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| CN202410501443.2A CN118068988B (en) | 2024-04-25 | 2024-04-25 | Self-capacitance touch detection circuit and detection method |
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| CN118068988B (en) | 2024-07-23 |
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