Touch detection circuit, method, chip and equipment

Abstract

The invention provides a touch detection circuit, a touch chip and touch equipment. The touch detection circuit comprises a switching circuit used for setting the voltage of a target electrode as a first preset voltage in a first stage in a scanning period and conducting the electrical connection between a non-target electrode and the ground, and used for disconnecting the electrical connection between the non-target electrode and the ground in a second stage in the scanning period and conducting the electrical connection between the non-target electrode and the ground in a third stage in the scanning period. And the electric connection between the target electrode and the non-target electrode is conducted. And the amplifying circuit is used for outputting the indicating voltage. Therefore, according to the touch detection circuit and method, the chip and the touch equipment provided by the invention, the non-target electrode can be used as the offset capacitor to bear the charge output by the target electrode during scanning, so that the manufacturing cost of the touch chip and the touch equipment is reduced.

Description

Technical Field

[0001] This application relates to the field of touch control, and more particularly, to a touch detection circuit, method, chip, and device. Background Art

[0002] In a touch device, a self-capacitance detection scheme is used to detect a user's touch operation. In the self-capacitance detection scheme, when a conductor approaches or touches a touch electrode in the touch device, the parasitic capacitance between the touch electrode and the ground will change. By detecting the change amount of the parasitic capacitance between the touch electrode and the ground, the touch position of the user can be obtained. Since the parasitic capacitance between the touch electrode and the ground is often relatively large, and the capacitance change amount caused by the conductor approaching or touching the detection electrode is small, it is necessary to set a cancellation capacitance similar to the capacitance of the parasitic capacitance to cancel the original parasitic capacitance between the touch electrode and the ground when the conductor approaches or touches the detection electrode, thereby improving the detection accuracy of the user's touch.

[0003] However, since the parasitic capacitance between the touch electrode and the ground is often relatively large, the capacitance and the layout area of the cancellation capacitance also need to be set relatively large, thus increasing the manufacturing cost of the touch chip and the device. Summary of the Invention

[0004] In view of the above problems, this application provides a touch detection circuit, method, chip, and device.

[0005] In a first aspect, a touch detection circuit is characterized by including: N receiving ports, respectively connected to corresponding N touch electrodes, and each touch electrode and the ground generate a corresponding parasitic capacitance. A switch circuit is configured to set the voltage of a target electrode to a first preset voltage and conduct the electrical connection between the non-target electrodes and the ground in a first stage within a scan cycle, and is configured to disconnect the electrical connection between the non-target electrodes and the ground and conduct the electrical connection between the target electrode and the non-target electrodes in a second stage within the scan cycle, where the target electrode is one of the N touch electrodes, and the non-target electrodes are the other N - 1 touch electrodes among the N touch electrodes. An amplification circuit is electrically connected to the N receiving ports through the switch circuit, receives a second preset voltage, and is configured to output an indication voltage according to the parasitic capacitance of the target electrode, the parasitic capacitance of the non-target electrodes, the first preset voltage, and the second preset voltage, and the change amount of the indication voltage is used to indicate the touch information of the target electrode. The first stage and the second stage are alternately executed to form a plurality of scan cycles.

[0006] In combination with the first aspect, in some possible implementation manners, the switch circuit includes N pull-up switches, N pull-down switches, and N interconnection switches that correspond to N touch electrodes one by one. One ends of the N pull-up switches all receive a first preset voltage, and the other ends of the N pull-up switches are respectively electrically connected to the corresponding N touch electrodes. One ends of the N pull-down switches are all grounded, and the other ends of the N pull-down switches are respectively electrically connected to the corresponding N touch electrodes. One ends of the N interconnection switches are respectively electrically connected to the corresponding N touch electrodes, and the other ends of the N interconnection switches are all electrically connected to the amplifier circuit.

[0007] In combination with the first aspect, in some possible implementation manners, in the first stage within the scanning period, the pull-up switch corresponding to the target electrode is turned on, the corresponding pull-down switch is turned off, the pull-up switches corresponding to the non-target electrodes are turned off, the corresponding pull-down switches are turned on, and all the N interconnection switches are turned off. In the second stage within the scanning period, the pull-up switches and the corresponding pull-down switches corresponding to the target electrode and the non-target electrodes are all turned off, and all the N interconnection switches are turned on.

[0008] In combination with the first aspect, in some possible implementation manners, the amplifier circuit includes an operational amplifier and a feedback capacitor, and the switch circuit further includes a feedback pull-up switch, a feedback parallel switch, and a feedback output switch. The inverting input terminal of the operational amplifier is electrically connected to the other ends of the N interconnection switches, one end of the feedback capacitor, and one end of the feedback parallel switch, and the non-inverting input terminal of the operational amplifier receives a second preset voltage. The other end of the feedback capacitor is electrically connected to one end of the feedback pull-up switch and one end of the feedback output switch, the other end of the feedback pull-up switch receives the first preset voltage, and the other end of the feedback output switch is electrically connected to the output terminal of the operational amplifier.

[0009] In combination with the first aspect, in some possible implementation manners, in the first stage within the scanning period, the feedback pull-up switch and the feedback parallel switch are turned on, and the feedback output switch is turned off. In the second stage within the scanning period, the feedback pull-up switch and the feedback parallel switch are turned off, and the feedback output switch is turned on.

[0010] In combination with the first aspect, in some possible implementation manners, the first preset voltage is N times the second preset voltage.

[0011] In a second aspect, the present application provides a touch detection method, which is applied to the touch detection circuit provided in any possible implementation manner of the first aspect. The method includes: in the first stage within the scanning period, setting the voltage of the target electrode to the first preset voltage and turning on the electrical connection between the non-target electrode and the ground; in the second stage within the scanning period, turning off the electrical connection between the non-target electrode and the ground and turning on the electrical connection between the target electrode and the non-target electrode, where the first stage and the second stage are alternately executed to form multiple scanning periods; and outputting an indication voltage according to the parasitic capacitance of the target electrode, the parasitic capacitance of the non-target electrode, the first preset voltage, and the second preset voltage.

[0012] In combination with the second aspect, in some possible implementation manners, the method further includes: adjusting the second preset voltage from the threshold voltage to the target voltage, so that when there is no touch on the target electrode, the indication voltage is the first preset voltage. Adjusting the change amount of the indication voltage from the real-time change amount to the calibration change amount, and the ratio of the calibration change amount to the real-time change amount is equal to the ratio of the target voltage to the threshold voltage.

[0013] In a third aspect, the present application provides a touch chip, including an analog-to-digital conversion circuit, an arithmetic circuit, and a touch detection circuit provided in any possible implementation manner of the first aspect. The analog-to-digital conversion circuit is configured to convert the change amount of the indication voltage into a digital signal. The arithmetic circuit is configured to output an indication signal according to the digital signal, and the indication signal is used to indicate the touch information of N touch electrodes.

[0014] In a fourth aspect, the present application provides a touch device, including a touch panel and a touch chip provided in any possible implementation manner of the third aspect. The touch panel includes N touch electrodes, and the touch chip is configured to detect the touch information of the N touch electrodes.

[0015] The touch detection circuit, method, chip, and touch device provided by the present application can use non-target electrodes as cancellation capacitors to carry the charges output during the scanning of the target electrode, reducing the manufacturing costs of the touch chip and the touch device. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of a touch device provided by an embodiment of the present application.

[0017] Figure 2 It is a schematic diagram of a touch chip provided by an embodiment of the present application.

[0018] Figure 3 It is a schematic diagram of a touch detection circuit provided by an embodiment of the present application.

[0019] Figure 4 It is a schematic diagram of a scanning wheel of a touch electrode provided by an embodiment of the present application.

[0020] Figure 5 It is a schematic diagram of the capacitance change amount of the parasitic capacitance of a touch electrode and the change amount of the indication voltage output by an amplifier circuit provided by an embodiment of the present application.

[0021] Figure 6 It is a schematic diagram of a touch detection method provided by an embodiment of the present application.

[0022] Figure 7 It is another schematic diagram of a touch detection method according to an embodiment of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] The technical solutions in the embodiments of the present application will be clearly described below in conjunction with the accompanying drawings in the embodiments of the present application.

[0024] It can be understood that the connection relationships described in the present application refer to direct or indirect connections. For example, when A is connected to B, it can be either that A is directly connected to B, or that A and B are indirectly connected through one or more other electrical components. For example, it can be that A is directly connected to C, and C is directly connected to B, so that A and B are connected through C. It can also be understood that "A is connected to B" described in the present application can be that A is directly connected to B, or that A and B are indirectly connected through one or more other electrical components.

[0025] In the description of the present application, unless otherwise specified, " / " means "or". For example, A / B can mean A or B. The "and / or" herein is only a description of the association relationship of the associated objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist simultaneously, and B exists alone.

[0026] In the description of the present application, terms such as "first" and "second" are only used to distinguish different objects, and do not limit the quantity and execution order, and the terms "first" and "second" do not necessarily mean different. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion.

[0027] Please refer to Figure 1 , Figure 1 which is a schematic diagram of a touch device 10 provided in an embodiment of the present application.

[0028] The touch device 10 includes a touch panel 11 and a touch chip 12. The touch panel 11 includes n touch electrodes S1 - Sn. Parasitic capacitances Crx1 - Crxn are respectively generated between the touch electrodes S1 - Sn and the ground. The touch electrodes S1 - Sn are all electrically connected to the touch chip 12.

[0029] When the touch panel 11 receives a touch operation, the parasitic capacitances Crx1 - Crxn corresponding to the touched touch electrodes S1 - Sn will change. The touch chip 12 can obtain the touch information of the touch electrodes S1 - Sn according to the change amounts of the parasitic capacitances Crx1 - Crxn corresponding to the touch electrodes S1 - Sn. For example, whether the touch electrodes S1 - Sn are touched, the specific positions of the touched touch electrodes S1 - Sn, etc.

[0030] Such as Figure 2As shown, n touch electrodes S1 - Sn are electrically connected to a touch chip 12 through touch electrode switches SW1 - SWn respectively. The touch chip 12 includes a plurality of switches, a cancellation capacitor CB, an operational amplifier CA, a feedback capacitor CF, an analog - to - digital conversion circuit, and an operational circuit (not shown in the figure).

[0031] The n touch electrodes S1 - Sn are electrically connected to an input bus 121 through the touch electrode switches SW1 - SWn respectively. One end of the input bus 121 is electrically connected to one end of a switch P11 and one end of a switch P21. The other end of the switch P11 receives a reference voltage VREF. The other end of the switch P21 is electrically connected to the inverting input terminal of the operational amplifier CA, one end of a switch P14, and one end of the feedback capacitor CF. The other end of the switch P14 is electrically connected to the other end of the feedback capacitor CF and the output terminal of the operational amplifier CA. One end of a switch P22 is electrically connected to the input bus 121. The other end of the switch P22 is electrically connected to one end of a switch P12 and one end of the cancellation capacitor CB. The other end of the cancellation capacitor CB receives the reference voltage VREF through a switch P13 and is grounded through a switch P23. The other end of the switch P12 is grounded.

[0032] When it is necessary to detect the touch information of the n touch electrodes S1 - Sn, each touch electrode S1 - Sn is sequentially conducted to the electrical connection of the input bus 121 through the corresponding touch electrode switch SW1 - SWn. For example, when the touch switch SW1 is conducted, the touch switches SW2 - SWn are disconnected. At this time, the touch electrode S1 is electrically connected to the input bus 121, while the touch electrodes S2 - Sn are disconnected from the electrical connection with the input bus 121. In addition, when the touch switch SW1 is conducted, the scanning cycle of the touch electrode S1 is entered. During the scanning cycle of the touch electrode S1, the touch chip 12 can obtain the touch information of the touch electrode S1. And so on. After the scanning cycle of the touch electrode S1 ends, the touch switch SW2 is conducted, the touch switches SW1, SW3 - SWn are disconnected. At this time, the touch electrode S2 is electrically connected to the input bus 121, while the touch electrodes S1, S3 - Sn are disconnected from the electrical connection with the input bus 121, and the scanning cycle of the touch electrode S2 is entered, and the touch chip 12 can obtain the touch information of the touch electrode S2. Thus, when the scanning cycles of all the touch electrodes S1 - Sn end, the touch chip 12 can obtain the touch information of the n touch electrodes S1 - Sn on the entire touch panel 11.

[0033] Among them, each scanning wheel includes multiple scanning cycles, and each scanning cycle includes a first stage and a second stage. Among them, the first stage is the reset stage. In this stage, switches P11, P13, P12, and P14 are turned on, while switches P21, P23, and P22 are turned off. The second stage is the charge transfer stage. In this stage, switches P21, P23, and P22 are turned on, while switches P11, P13, P12, and P14 are turned off. The reset stage and the charge transfer stage are alternately executed to form multiple scanning cycles.

[0034] Taking one scanning cycle of the touch electrode S1 as an example, in the reset stage, since switches P11, P13, P12, and P14 are turned on, while switches P21, P23, and P22 are turned off, the voltage of the parasitic capacitance Crx1 of the touch electrode S1 is pulled up to the reference voltage VREF. In the charge transfer stage, since switches P21, P23, and P22 are turned on, while switches P11, P13, P12, and P14 are turned off, the charges accumulated on the parasitic capacitance Crx1 corresponding to the touch electrode S1 and the charges accumulated on the cancellation capacitance CB are neutralized with each other, and the voltages of the parasitic capacitance Crx1 of the touch electrode S1, the cancellation capacitance CB, and the feedback capacitance CF gradually stabilize. According to the circuit structure of the touch chip 12, the output voltage CAOUT of the operational amplifier CA satisfies the following formula (1).

[0035] 。

[0036] Among them, Crx1 is the capacitance value of the parasitic capacitance generated by the touch electrode S1, CB is the capacitance value of the cancellation capacitance, CF is the capacitance value of the feedback capacitance, and VREF is the reference voltage value.

[0037] The analog-to-digital conversion circuit receives the output voltage CAOUT of the operational amplifier CA and generates a corresponding digital signal according to the change amount of the output voltage CAOUT of the operational amplifier CA. The operation circuit outputs an indication signal according to the digital signal, so that the indication signal indicates the touch information of the N touch electrodes S1 - Sn. Specifically, the analog-to-digital conversion circuit generates a corresponding digital signal according to the change amount of the output voltage CAOUT of the operational amplifier CA. Compared with generating a corresponding digital signal according to the output voltage CAOUT of the operational amplifier CA, it can avoid measuring the absolute value of the output voltage CAOUT of the operational amplifier CA, simplifies the circuit design, reduces the complexity, and reduces the circuit power consumption. At the same time, it is not necessary to calibrate or adjust the circuit to eliminate the initial bias voltage of the operational amplifier CA, improving the reliability of detection. In addition, when the touch device 10 is interfered, the change amount of the output voltage CAOUT of the operational amplifier CA can still accurately reflect the true touch information of the touch electrodes S1 - Sn, enhancing the robustness of touch detection.

[0038] Based on this, according to formula (1), the change amount ΔCAOUT of the output voltage CAOUT of the operational amplifier CA satisfies the following formula (2).

[0039] 。

[0040] Wherein, ΔCrx is the change amount of the capacitance value of the touch electrode. When the touch electrode is touched, the capacitance value of the touch electrode will increase. The analog-to-digital conversion circuit can convert the change amount ΔCAOUT of the output voltage CAOUT of the operational amplifier CA into a corresponding digital signal for subsequent digital processing by the arithmetic circuit. After the arithmetic circuit performs digital processing on the digital signal, the touch information of the N touch electrodes S1 - Sn can be obtained.

[0041] However, since the capacitance values of each touch electrode are generally not exactly the same, before the start of the scanning cycle of each touch electrode, it is necessary to adjust the capacitance value of the cancellation capacitor CB so that the capacitance value of the cancellation capacitor CB is approximately equal to or of the same order of magnitude as the parasitic capacitance value of the touch electrode currently being scanned and detected, thereby preventing the indication voltage CAOUT output by the operational amplifier CA from saturating, affecting the touch detection result or even causing the touch detection to fail.

[0042] Therefore, the present application provides a touch detection circuit 100. By using non-target electrodes, that is, the touch electrodes S1 - Sn that are not currently being scanned or touch-detected, as the cancellation capacitor CB to carry the charge output during the scanning of the target electrode, the setting of the cancellation capacitor CB can be omitted, thereby reducing the manufacturing cost of the touch chip.

[0043] Specifically, please refer to Figure 3 , Figure 3 which is a schematic diagram of the touch detection circuit 100 provided by an embodiment of the present application. The touch detection circuit 100 includes N receiving ports, a switch circuit, and an amplification circuit. The operational amplifier CA, the feedback capacitor CF, the voltage-dividing resistor RH, and the voltage-dividing resistor RL constitute the amplification circuit.

[0044] Each receiving port is correspondingly electrically connected to a touch electrode. For example, receiving port 1 is correspondingly electrically connected to touch electrode S1, and receiving port N is correspondingly electrically connected to touch electrode Sn. Each touch electrode forms a parasitic capacitance with the ground. For example, touch electrode S1 forms a parasitic capacitance Crx1 with the ground.

[0045] The switch circuit includes N pull-up switches, N pull-down switches, N interconnection switches P2, a feedback pull-up switch PHf, a feedback parallel switch P1, and a feedback output switch Po, which correspond to N touch electrodes one by one. One ends of the N pull-up switches all receive a first preset voltage VH, and the other ends of the N pull-up switches are respectively electrically connected to the corresponding N touch electrodes S1-Sn. One ends of the N pull-down switches are all grounded, and the other ends of the N pull-down switches are respectively electrically connected to the corresponding N touch electrodes S1-Sn. One ends of the N interconnection switches P2 are respectively electrically connected to the corresponding N touch electrodes S1-Sn, and the other ends of the N interconnection switches P2 are all electrically connected to the inverting input terminal of the operational amplifier CA, one end of the feedback capacitor CF, and one end of the feedback parallel switch P1. The non-inverting input terminal of the operational amplifier CA receives a second preset voltage VL. The other end of the feedback capacitor CF is electrically connected to one end of the feedback pull-up switch PHf and one end of the feedback output switch Po. The other end of the feedback pull-up switch PHf receives the first preset voltage VH, and the other end of the feedback output switch Po is electrically connected to the output terminal of the operational amplifier CA.

[0046] Specifically, one ends of the pull-up switches PH1, ……, PHk, ……, PHn all receive the first preset voltage VH, and the other ends of the pull-up switches PH1, ……, PHk, ……, PHn are respectively correspondingly electrically connected to the receiving ports, that is, the other ends of the pull-up switches PH1, ……, PHk, ……, PHn are respectively correspondingly electrically connected to the touch electrodes S1-Sn. One ends of the pull-down switches PL1, ……, PLk, ……PLn are all grounded, and the other ends of the pull-down switches PL1, ……, PLk, ……PLn are respectively correspondingly electrically connected to the receiving ports, that is, the other ends of the pull-down switches PL1, ……, PLk, ……PLn are respectively correspondingly electrically connected to the touch electrodes S1-Sn. In addition, each of the touch electrodes S1-Sn is electrically connected to one end of the corresponding interconnection switch P2 through the corresponding receiving port. The other end of each interconnection switch P2 is electrically connected to the inverting input terminal of the operational amplifier CA. The non-inverting input terminal of the operational amplifier CA is electrically connected to one ends of a voltage-dividing resistor RH and a voltage-dividing resistor RL. The other end of the voltage-dividing resistor RH receives the first preset voltage VH, and the other end of the voltage-dividing resistor RL is grounded.

[0047] In some embodiments, the voltage-dividing resistor RL can be an adjustable resistor. Thus, by adjusting the resistance value of the voltage-dividing resistor RL, the voltage-dividing relationship between the voltage-dividing resistor RH and the voltage-dividing resistor RL can be adjusted, and thus the voltage value of the second preset voltage VL received by the operational amplifier CA can be adjusted.

[0048] Based on the circuit structure of the touch detection circuit 100, the scanning cycle of the touch electrode Sk will be described below taking the touch electrode Sk as an example.

[0049] Please refer to Figure 4 ,Figure 4 This is a schematic diagram of the scanning wheel of the touch electrode Sk provided by an embodiment of the present application. Among them, one frame of touch detection of the touch panel 11 includes multiple touch electrode scanning wheels, and each touch electrode scanning wheel is performed in sequence. That is, one frame of touch detection period of the touch panel 11 starts from the scanning wheel of the touch electrode S1 and ends with the scanning wheel of the touch electrode Sn. In each stage of the scanning wheel of each touch electrode, the touch chip 12 can obtain the touch information of the corresponding touch electrode. Therefore, when the scanning wheel of the touch electrode Sn ends, one frame of touch detection of the touch panel 11 ends, and the touch chip 12 can obtain the touch information of all touch electrodes, so as to obtain whether the touch panel 11 receives a touch operation and the specific touch electrode being touched, and thus can accurately locate the touch position.

[0050] Taking the Sk scanning wheel as an example, the Sk scanning wheel includes multiple Sk scanning cycles, and the operational amplifier CA can output a corresponding indication voltage according to the parasitic capacitance Crxk of the touch electrode Sk in each Sk scanning cycle. When the touch electrode Sk receives a touch operation, the parasitic capacitance Crxk of the touch electrode Sk will change, and the indication voltage output by the operational amplifier CA will also change. Thus, the analog-to-digital conversion circuit can convert the change amount ΔCAOUT of the output voltage CAOUT of the operational amplifier CA into a corresponding digital signal for subsequent digital processing by the arithmetic circuit. After the arithmetic circuit performs digital processing on the digital signal, the touch information of the touch electrode Sk can be obtained.

[0051] Specifically, one Sk scanning cycle includes a reset stage and a charge transfer stage. In the reset stage, the touch electrode that is currently in the scanning and touch detection state, that is, the target electrode, here is the touch electrode Sk, and its corresponding pull-up switch PHk is turned on, and the pull-down switch PLk is turned off. The touch electrodes that are not currently in the scanning and touch detection state, that is, the non-target electrodes, here are all electrodes other than the touch electrode Sk, and their corresponding pull-up switches are turned off, and the pull-down switches are turned on. That is, the pull-up switches PH1 - PH(k - 1), PH(k + 1) - PHn are turned off, and the pull-down switches PL1 - PL(k - 1), PL(k + 1) - PLn are turned on. In addition, all N interconnection switches P2 are turned off, the feedback pull-up switch PHf and the feedback parallel switch P1 are turned on, and the feedback output switch Po is turned off.

[0052] Therefore, during the reset phase, the target electrode receives a first preset voltage VH through the corresponding pull-up switch, that is, the switch circuit sets the voltage of the target electrode to the first preset voltage VH during the reset phase of the scanning period. At this time, the parasitic capacitance of the target electrode, here Crxk, is charged, and the voltage of the touch electrode Sk rises. When the parasitic capacitance Crxk is fully charged, the voltage of the touch electrode Sk rises to the first preset voltage VH. According to the virtual short principle of the operational amplifier CA, the voltage at the inverting input terminal of the operational amplifier CA and the indicated voltage CAOUT at the output terminal are both equal to the second preset voltage VL received at the non-inverting input terminal. The voltage VCF at the right node of the feedback capacitor CF is pulled up to the first preset voltage VH by the feedback pull-up switch PHf. In addition, during the reset phase, the non-target electrodes are grounded through the corresponding pull-down switches, that is, the switch circuit conducts the electrical connection between the non-target electrodes and the ground during the reset phase of the scanning period. At this time, the non-target electrodes, that is, the touch electrodes S1 - S(k - 1), S(k + 1) - Sn are grounded, and the voltages of the touch electrodes S1 - S(k - 1), S(k + 1) - Sn remain at the ground level.

[0053] During the charge transfer phase, the pull-up switch corresponding to the target electrode is turned off, the pull-down switch is turned off, and the pull-down switches corresponding to the non-target electrodes are turned off. In addition, all N cross switches P2 are turned on, the feedback pull-up switch PHf and the feedback parallel switch P1 are turned off, and the feedback output switch Po is turned on. The right node of the feedback capacitor CF is electrically connected to the output terminal of the operational amplifier CA, so that the voltage VCF at the right node of the feedback capacitor CF is the indicated voltage CAOUT.

[0054] Therefore, during the charge transfer phase, the target electrode is electrically connected to all non-target electrodes through the corresponding cross switches P2. Thus, all the charges accumulated after the parasitic capacitance of the target electrode is fully charged are transferred to the parasitic capacitances corresponding to all non-target electrodes. That is, the parasitic capacitances corresponding to the non-target electrodes carry the charges accumulated after the parasitic capacitance of the target electrode is fully charged, thereby ensuring that the indicated voltage CAOUT output by the operational amplifier CA does not saturate. At this time, the voltage of the touch electrode Sk decreases as the charge amount of the parasitic capacitance Crxk decreases, and the voltages of the non-target electrodes increase as they receive the charges from the touch electrode Sk. When the charges on the parasitic capacitance of the target electrode are transferred to the parasitic capacitances of the non-target electrodes, the voltages of the target electrode and the non-target electrodes will tend to be stable. At this time, the indicated voltage CAOUT output by the operational amplifier CA satisfies the following formula (3).

[0055] 。

[0056] Wherein, Crxk is the capacitance value corresponding to the target electrode. Crxo is the total capacitance value corresponding to the non-target electrodes. VH is the voltage value of the first preset voltage, VL is the voltage value of the second preset voltage, Cf is the capacitance value of the feedback capacitor, and at this moment, the indication voltage CAOUT is equal to the voltage VCF at the right node of the feedback capacitor CF.

[0057] Since the indication voltage CAOUT output by the operational amplifier CA is associated with the second preset voltage VL, the second preset voltage VL can be adjusted so that the indication voltage CAOUT output by the operational amplifier CA is within a reasonable voltage range. In some embodiments, when the indication voltage CAOUT output by the operational amplifier CA is configured as the first preset voltage VH when the touch panel 11 does not receive a touch operation, the indication voltage CAOUT output by the operational amplifier CA satisfies formula (3). In some embodiments, the parasitic capacitances Crx1 - Crxn corresponding to all the touch electrodes S1 - Sn are relatively close to each other, so the parasitic capacitance of the target electrode is approximately equal to the average value of all the target capacitances. According to formula (3), the first preset voltage VH can be obtained as n times the second preset voltage VL. Thus, by configuring the second preset voltage VL as one nth of the first preset voltage VH, the indication voltage CAOUT output by the operational amplifier CA can be within a reasonable voltage range, improving the accuracy of touch detection.

[0058] When the target electrode and / or the adjacent touch electrode receives a touch operation, the parasitic capacitance corresponding to the target electrode and / or the adjacent touch electrode will change. At this time, the change amount ΔCAOUT of the indication voltage CAOUT output by the operational amplifier CA satisfies formula (4) as follows.

[0059] 。

[0060] When the number of touch electrodes is large, for example, when the number N of touch electrodes ≥ 10, the following can be deduced from formula (4).

[0061] 。

[0062] Therefore, ΔCAOUT is proportional to ΔCrxk, and thus the touch information of the target electrode can be detected through ΔCAOUT.

[0063] Please refer to Figure 5 , Figure 5 Figure (a) in Figure 5Figure (b) in [the figure] is a schematic diagram of the capacitance change of the touch electrode and the change of the indication voltage output by the operational amplifier CA. Here, N = 20, the capacitance value range of each parasitic capacitance is 300 pF ± 20%, the first preset voltage VH = 3.3 V, the second preset voltage VL = 0.165 V, the capacitance value of the feedback capacitor Cf is 10 pF. The touch electrode S8 and the adjacent touch electrodes S5 - S13 generate capacitance changes due to touch operations. Among them, the change amount of the parasitic capacitance Crx8 corresponding to the touch electrode S8 is 0.2 pF, and the change amounts of the parasitic capacitances corresponding to the remaining adjacent touch electrodes gradually decrease with the increase of the distance from the touch electrode S8. The touch circuit provided in this embodiment has high precision.

[0064] As Figure 5 shown, when the touch electrode S8 receives a touch operation, the change amount ΔCAOUT of the indication voltage output by the operational amplifier CA decreases significantly. Furthermore, the analog-to-digital conversion circuit and the arithmetic circuit can accurately obtain that the touch electrodes S5 - S13 are affected by the touch operation, and the specific position where the touch operation occurs is the touch electrode S8.

[0065] Please refer to Figure 6 , Figure 6 which is a schematic diagram of the touch detection method provided by an embodiment of the present application. The touch detection method can be applied to the touch detection circuit 100 provided by the present application. Specifically, the touch detection circuit 100 may further include a control circuit. Among them, the touch detection method may include the following steps.

[0066] Step S1, in the first stage of the scanning period, set the voltage of the target electrode to the first preset voltage VH, and conduct the electrical connection between the non-target electrode and the ground.

[0067] Specifically, step S1 can be executed by the control circuit. The first stage in the scanning period is the reset stage. In this stage, the control circuit can output a first control signal to control the conduction or disconnection of multiple switches. For example, the control circuit can output the first control signal to the switch circuit, so that the pull-up switch corresponding to the target electrode conducts, the pull-down switch disconnects, the pull-up switch corresponding to the non-target electrode disconnects, and the pull-down switch conducts. In addition, the first control signal can also make all N interconnection switches P2 disconnect, the feedback pull-up switch PHf and the feedback parallel switch P1 conduct, and the feedback output switch Po disconnect. Thus, the voltage of the target electrode is set to the first preset voltage VH, and the electrical connection between the non-target electrode and the ground is conducted.

[0068] Step S2, in the second stage of the scanning period, disconnect the electrical connection between the non-target electrode and the ground, and conduct the electrical connection between the target electrode and the non-target electrode.

[0069] Specifically, step S2 can be executed by the control circuit. The second stage within the scanning period is the charge transfer stage. During this stage, the control circuit can output a second control signal to control the conduction or disconnection of multiple switches. For example, the control circuit can output the second control signal to the switch circuit, causing the pull-up switch corresponding to the target electrode to disconnect, and the pull-down switch corresponding to the non-target electrode to disconnect. The pull-down switches of all touch electrodes remain disconnected. In addition, the second control signal can also cause all N interconnection switches P2 to conduct, the feedback pull-up switch PHf and the feedback parallel switch P1 to disconnect, and the feedback output switch Po to conduct. Thereby, the electrical connection between the non-target electrode and the ground is disconnected, and the electrical connection between the target electrode and the non-target electrode is conducted.

[0070] Step S3: Output an indication voltage based on the parasitic capacitance of the target electrode, the parasitic capacitance of the non-target electrode, the first preset voltage, and the second preset voltage.

[0071] Among them, step S3 can be executed by the operational amplifier CA. The relationship between the indication voltage and the parasitic capacitance of the target electrode, the parasitic capacitance of the non-target electrode, the first preset voltage VH, and the second preset voltage VL can refer to the description of formula (3), which will not be elaborated here.

[0072] In some embodiments, during touch detection, the indication voltage output by the operational amplifier CA may be oversaturated. For this reason, before scanning each target electrode, the second preset voltage VL can be adaptively adjusted, so that the indication voltage CAOUT output by the operational amplifier CA is configured as the first preset voltage VH when the touch panel 11 does not receive a touch operation, thereby solving the problem that the indication voltage output by the operational amplifier CA may be oversaturated due to a large difference in the parasitic capacitances corresponding to multiple touch electrodes S1 - Sn.

[0073] Specifically, as Figure 7 shown, the touch detection method may further include the following steps.

[0074] Step S4: Adjust the second preset voltage VL from the threshold voltage to the target voltage, so that when there is no touch on the target electrode, the indication voltage is the first preset voltage VH.

[0075] Among them, step S4 can be executed by the control circuit before step S1. The threshold voltage is the second preset voltage VL before calibration. The target voltage is the voltage value of the second preset voltage VL that can make the indication voltage output by the operational amplifier CA be the first preset voltage VH when there is no touch on the target electrode. In this way, by calibrating the second preset voltage VL, it can be ensured that the indication voltage output by the operational amplifier CA is within a reasonable voltage range, thereby enabling accurate touch detection.

[0076] Step S5: Adjust the change amount of the indication voltage from the real-time change amount to the calibration change amount. The ratio of the calibration change amount to the real-time change amount is equal to the ratio of the target voltage to the threshold voltage.

[0077] Among them, step S5 can be executed by the control circuit after step S3. The real-time change amount is the change amount of the indication voltage output by the operational amplifier CA in step S3. By adjusting the real-time change amount to the calibration change amount, the change amount of the indication voltage can be calibrated according to the ratio of the second preset voltage VL after calibration to the second preset voltage VL before calibration, so that the result of touch detection can be obtained more accurately.

[0078] Thus, the touch detection circuit 100, method, touch chip 12 and touch device 10 provided by the present application can use the non-target electrode as the cancellation capacitor CB to carry the charge output during the scanning of the target electrode, reducing the manufacturing cost of the touch chip 12 and further facilitating the cost reduction of the touch device 10.

[0079] Those of ordinary skill in the art of the present technology should recognize that the above embodiments are only used to illustrate the present application, rather than to limit the present application. As long as within the scope of the spirit of the present application, appropriate changes and variations made to the above embodiments fall within the scope of protection required by the present application.

Claims

1. A touch detection circuit, characterized in that, Comprising: N receiving ports, respectively connected to corresponding N touch electrodes, and each touch electrode generates a corresponding parasitic capacitance with the ground; A switch circuit, configured to set the voltage of a target electrode to a first preset voltage in a first stage within a scanning period, conduct the electrical connection between non-target electrodes and the ground, and configured to disconnect the electrical connection between non-target electrodes and the ground and conduct the electrical connection between the target electrode and the non-target electrodes in a second stage within the scanning period, wherein the target electrode is one of the N touch electrodes, and the non-target electrodes are the other N-1 of the N touch electrodes; An amplifying circuit, electrically connected to the N receiving ports through the switch circuit, receiving a second preset voltage, and configured to output an indication voltage according to the parasitic capacitance of the target electrode, the parasitic capacitance of the non-target electrodes, the first preset voltage, and the second preset voltage, and the change amount of the indication voltage is used to indicate the touch information of the target electrode; The first stage and the second stage are alternately executed to form a plurality of the scanning periods.

2. The touch detection circuit according to claim 1, wherein The switch circuit includes N pull-up switches, N pull-down switches, and N interconnection switches corresponding one by one to the N touch electrodes; One ends of the N pull-up switches all receive the first preset voltage, and the other ends of the N pull-up switches are respectively electrically connected to the corresponding N touch electrodes; One ends of the N pull-down switches are all grounded, and the other ends of the N pull-down switches are respectively electrically connected to the corresponding N touch electrodes; One ends of the N interconnection switches are respectively electrically connected to the corresponding N touch electrodes, and the other ends of the N interconnection switches are all electrically connected to the amplifying circuit.

3. The touch detection circuit according to claim 2, wherein In the first stage within the scanning period, the pull-up switch corresponding to the target electrode is conducted, the corresponding pull-down switch is disconnected, the pull-up switches corresponding to the non-target electrodes are disconnected, the corresponding pull-down switches are conducted, and the N interconnection switches are all disconnected; In the second stage within the scanning period, the pull-up switches and the corresponding pull-down switches corresponding to the target electrode and the non-target electrodes are all disconnected, and the N interconnection switches are all conducted.

4. The touch detection circuit according to claim 2, wherein The amplifying circuit includes an operational amplifier and a feedback capacitor, and the switch circuit further includes a feedback pull-up switch, a feedback parallel switch, and a feedback output switch; The inverting input terminal of the operational amplifier is electrically connected to the other ends of the N interconnection switches, one end of the feedback capacitor, and one end of the feedback parallel switch, and the non-inverting input terminal of the operational amplifier receives the second preset voltage; The other end of the feedback capacitor is electrically connected to one end of the feedback pull-up switch and one end of the feedback output switch, the other end of the feedback pull-up switch receives the first preset voltage, and the other end of the feedback output switch is electrically connected to the output terminal of the operational amplifier.

5. The touch detection circuit according to claim 4, wherein In the first stage within the scanning period, the feedback pull-up switch and the feedback parallel switch are conducted, and the feedback output switch is disconnected; In the second stage within the scanning period, the feedback pull-up switch and the feedback parallel switch are disconnected, and the feedback output switch is conducted.

6. The touch detection circuit according to claim 4, wherein The first preset voltage is N times the second preset voltage.

7. A touch detection method, applied to the touch detection circuit according to any one of claims 1 to 6, characterized in that, The method includes: In the first stage within the scanning period, set the voltage of the target electrode to the first preset voltage and conduct the electrical connection between the non-target electrode and the ground; In the second stage within the scanning period, disconnect the electrical connection between the non-target electrode and the ground and conduct the electrical connection between the target electrode and the non-target electrode, wherein the first stage and the second stage are alternately executed to form a plurality of the scanning periods; output the indication voltage according to the parasitic capacitance of the target electrode, the parasitic capacitance of the non-target electrode, the first preset voltage, and the second preset voltage.

8. The touch detection method according to claim 7, wherein, The method further includes: Adjust the second preset voltage from the threshold voltage to the target voltage so that when there is no touch on the target electrode, the indication voltage is the first preset voltage; Adjust the change amount of the indication voltage from the real-time change amount to the calibration change amount, and the ratio of the calibration change amount to the real-time change amount is equal to the ratio of the target voltage to the threshold voltage.

9. A touch chip, characterized in that, It includes an analog-to-digital conversion circuit, an arithmetic circuit, and the touch detection circuit according to any one of claims 1 to 6; The analog-to-digital conversion circuit is used to convert the change amount of the indication voltage into a digital signal; The arithmetic circuit is used to output an indication signal according to the digital signal, and the indication signal is used to indicate the touch information of the N touch electrodes.

10. A touch device, characterized in that, It includes a touch panel and the touch chip according to claim 9, the touch panel includes N touch electrodes, and the touch chip is used to detect the touch information of the N touch electrodes.

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