Capacitive sensor and circuit fault self-detection method thereof

Abstract

The present invention discloses a capacitive sensor, including a controller, a capacitor, a first current-limiting resistor, a connector and a sensing electrode connected in series with a first pin of the controller in sequence; the first end of the first current-limiting resistor and the capacitor is connected to the second pin of the controller; it also includes a power supply component and a voltage-dividing resistor, and the high-level output end of the power supply component is used to connect to the first end or the second end of the first current-limiting resistor through the voltage-dividing resistor; the controller is used to control the connection between the power supply component and the first current-limiting resistor when the fault self-check is started, and control the sensing terminal connected to the connector and the sensing electrode to connect to the low-level signal, and collect the electrical signal through the second pin, so as to determine whether there is a circuit fault according to the size of the electrical signal. The present application can automatically detect the circuit fault of the capacitive sensor and improve the user experience. The present application also provides a circuit fault self-check method for a capacitive sensor, which has the above-mentioned beneficial effects.

Description

Technical Field

[0001] The present invention relates to the technical field of sensor fault detection, and in particular to a capacitive sensor and a circuit fault self-detection method of the capacitive sensor. Background Art

[0002] Capacitive sensors use the change in capacitance caused by the object being measured to determine the state of the object being measured. For example, capacitive touch sensors are commonly found in touch screens of various electronic devices. The sensing electrodes on the touch screen sense the touch of a finger or the like, which causes the corresponding induced voltage to change. The touch output command signal can be determined based on the change in the induced voltage.

[0003] In order to detect the change of the induced voltage in the capacitive sensor, a circuit structure for detecting the induced voltage needs to be configured. However, in the actual application process, this circuit structure will inevitably fail, which directly leads to the unavailability of the capacitive sensor. Summary of the invention

[0004] The purpose of the present invention is to provide a capacitive sensor and a circuit fault self-detection method for the capacitive sensor, which can accurately detect circuit faults of the capacitive sensor and is beneficial to fault judgment when the capacitive sensor is used in electronic equipment.

[0005] In order to solve the above technical problems, the present invention provides a capacitive sensor, comprising: a controller, and a capacitor, a first current limiting resistor, a connector, and a sensing electrode connected in series with a first pin of the controller in sequence; a first end of the first current limiting resistor connected to the capacitor is connected to a second pin of the controller;

[0006] It also includes a power supply component and a voltage-dividing resistor, wherein the high-level output end of the power supply component is used to connect to the first end or the second end of the first current-limiting resistor through the voltage-dividing resistor;

[0007] The controller is used to control the connection between the power supply component and the first current limiting resistor when the fault self-check is started, and control the sensing terminal connected to the connector and the sensing electrode to connect a low-level signal, and collect the electrical signal through the second pin of the controller, so as to determine whether there is a circuit fault according to the size of the electrical signal.

[0008] Optionally, the power supply component includes a power supply and a first power switch, and the high-level output end of the power supply is connected to the first current-limiting resistor through the first power switch; and the controller is used to control the disconnection and connection of the first power switch.

[0009] Optionally, the power supply component also includes a second power supply switch for connecting the low-level output terminal of the power supply and the sensing terminal of the connector; the controller is used to synchronously control the disconnection and connection of the first power supply switch and the second power supply switch.

[0010] Optionally, the power supply component is a built-in power supply device of the controller, and is connected to the first current limiting resistor through a third pin of the controller. The controller is used to control the third pin to output a high-level signal when starting fault self-check.

[0011] Optionally, a fourth pin of the controller is connected to a sensing terminal of the connector, so as to output a low level signal through the fourth pin when the fault self-check is started.

[0012] Optionally, a second current limiting resistor is further arranged between the fourth pin of the controller and the connector.

[0013] The present application also provides a circuit fault self-detection method for a capacitive sensor, which is applied to the capacitive sensor as described in any one of the above items, comprising:

[0014] Outputting low-level signals respectively through the first pin and the second pin of the controller in advance so that the capacitor voltage corresponding to the capacitor reaches a stable state;

[0015] Control the power supply component to connect a high level signal to the first current limiting resistor, and the sensing terminal of the connector to connect a low level signal;

[0016] Switching the second pin of the controller to a state of collecting voltage signals to collect an electrical signal from a first end or a second end of the first current limiting resistor;

[0017] It is determined whether the magnitude of the electrical signal is within a preset voltage range; if not, there is a circuit fault.

[0018] Optionally, determining whether the magnitude of the electrical signal is within a normal voltage range includes:

[0019] The electrical signal is a voltage signal;

[0020] When the voltage signal is less than a first preset voltage value, the capacitor is short-circuited;

[0021] When the voltage signal is greater than the first preset voltage value and less than the minimum normal voltage value, or the voltage signal is greater than the maximum normal voltage value and less than the second preset voltage value, there is a circuit element parameter drift; wherein the voltage range between the minimum normal voltage value and the maximum normal voltage value is the normal voltage range;

[0022] When the voltage signal is greater than the second preset voltage signal value, a circuit break fault exists.

[0023] Optionally, it also includes:

[0024] After determining that the electrical signal is within the preset voltage range, the third pin and the fourth pin of the controller are controlled to switch to a receiving pin state, so that the third pin and the fourth pin are in a high impedance state.

[0025] A capacitive sensor provided by the present invention comprises a controller, a capacitor, a first current limiting resistor, a connector and a sensing electrode which are connected in series with a first pin of the controller in sequence; a first end of the first current limiting resistor connected to the capacitor is connected to a second pin of the controller; a power supply component and a voltage dividing resistor are also included, and a high-level output end of the power supply component is used to be connected to the first end or the second end of the first current limiting resistor through the voltage dividing resistor; the controller is used to control the power supply component and the first current limiting resistor to be connected when the fault self-check is started, and to control the sensing terminal connected to the connector and the sensing electrode to be connected to a low-level signal, and to collect electrical signals through the second pin, so as to determine whether there is a circuit fault according to the size of the electrical signal.

[0026] In the capacitive sensor of the present application, the capacitor, the first current limiting resistor, the connector and the sensing electrode connected in series in sequence form a circuit for detecting the induced voltage. On this basis, the present application further provides a power supply component interconnected with any end of the first current limiting resistor, and controls the disconnection and closing between the power supply component and the first current limiting resistor and whether the sensing terminal of the connector is connected to a low-level signal by a controller, so as to realize the start or not of the fault detection in the capacitive sensor. Because the first pin of the controller outputs a low-level signal to the capacitor, when the power supply component and the first current limiting resistor are connected, and the sensing terminal of the connector is connected to a low-level signal, two circuit branches can be formed from the power supply component to the first pin and from the power supply resistor to the sensing terminal of the connector, wherein the circuit element disconnection, parameter drift or short circuit on any circuit branch can be reflected from the electrical signal similar to voltage or current detected at the second pin of the controller, thereby realizing self-detection of whether the circuit element in the capacitive sensor is faulty, which is conducive to timely discovery of the capacitive sensor fault, and is convenient for quickly troubleshooting whether the fault cause is the capacitive sensor fault when the device containing the capacitive sensor fails, thereby improving the user experience.

[0027] The present application also provides a circuit fault self-detection method for a capacitive sensor, which has the above-mentioned beneficial effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 A schematic diagram of the circuit structure of a capacitive sensor provided in an embodiment of the present application;

[0030] Figure 2 Another schematic diagram of the circuit structure of the capacitive sensor provided in the embodiment of the present application;

[0031] Figure 3 A schematic flow chart of a circuit fault self-detection method for a capacitive sensor provided in an embodiment of the present application. DETAILED DESCRIPTION

[0032] When capacitive sensors are used in various electronic devices or other equipment, if a fault occurs in the capacitive sensor and affects the normal operation of the electronic device, there is no quick way to determine whether the fault is with the capacitive sensor, but it is necessary to determine whether other components in the electronic device are faulty. Obviously, this greatly reduces the efficiency of troubleshooting the electronic sensor.

[0033] To this end, the present application provides a technical solution that can more quickly identify and determine capacitive sensor faults.

[0034] In order to enable those skilled in the art to better understand the scheme of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0035] like Figure 1 and Figure 2 As shown, Figure 1 A schematic diagram of the circuit structure of a capacitive sensor provided in an embodiment of the present application, Figure 2 Another circuit structure diagram of a capacitive sensor provided in an embodiment of the present application, the capacitive sensor may include:

[0036] A controller, a capacitor Cs, a first current limiting resistor R1, a connector and a sensing electrode connected in series with a first pin P1 of the controller; a first end where the first current limiting resistor R1 and the capacitor Cs are connected is connected to a second pin P2 of the controller.

[0037] Based on the common knowledge of the working principle of a capacitive sensor, it is known that a capacitive sensor includes two conductive layers equivalent to capacitor plates, and one of the two conductive layers is electrically connected to a sensing electrode.

[0038] Taking touch sensing as an example, when a finger touches and presses on the touch sensing screen, the voltage difference between the two conductive layers can change, and the change of this voltage difference is transmitted to the controller in the form of an electrical signal through the sensing electrode through the connector and the first current limiting resistor R1. The controller collects this electrical signal and can determine that the finger has performed a touch operation on the touch screen.

[0039] On this basis, the present application may further include:

[0040] A power supply component and a voltage-dividing resistor R3, wherein the high-level output end of the power supply component is used to connect to the first end or the second end of the first current-limiting resistor R1 through the voltage-dividing resistor R3;

[0041] The controller is used to control the connection between the power supply component and the first current limiting resistor R1 when the fault self-check is started, and to control the sensing terminal connected to the connector and the sensing electrode to connect the low-level signal, and to collect the electrical signal through the second pin P2, so as to determine whether there is a circuit fault according to the size of the electrical signal.

[0042] It should be noted that the possible circuit faults of capacitive sensors can mainly include the following:

[0043] 1) The first current limiting resistor R1 is open circuit or parameter drifts;

[0044] 2) The connector or the path between the connector and the sensing electrode is disconnected or the parameters drift;

[0045] 3) The collection capacitor Cs is short-circuited.

[0046] Then, when it is necessary to perform a fault self-check on the capacitive sensor, it is first necessary to set the first pin P1 connecting the controller and the capacitor Cs to a low level state. When the first end of the first current limiting resistor R1 and the high level output end of the power supply component are connected through the voltage divider resistor R3, the power supply component outputs a high level signal, and the first pin P1 of the controller is a low level. Thus, a energized branch can be formed from the high level output end of the power supply component, the voltage divider resistor R3, the first current limiting resistor R1, the capacitor Cs to the second pin P2 of the controller.

[0047] At the same time, a power-on branch circuit can also be formed between the high-level output terminal of the power supply component, the voltage-dividing resistor R3 and the low-level connection of the sensing terminal of the connector.

[0048] When there is no circuit fault in the entire circuit, the capacitor Cs is equivalent to an open circuit, and only a circuit path is formed from the high-level output end of the power supply component to the voltage divider resistor R3, and the induction terminal of the connector to the connector. At this time, the voltage signal at the point where the voltage divider resistor R3 and the first end of the first current limiting resistor R1 are connected measured by the second pin P2 of the controller should meet the following requirements:

[0049] U=[(U1-U2) / (R1+R2+R3+R4+R5)]*R1; wherein R1 is the first current limiting resistor, R2 is the equivalent resistance of the connector wire, R3 is the voltage dividing resistor, R4 is the second current limiting resistor, and R5 is the equivalent resistance of the wire; U1 is the high-level signal output by the pressure supply component, and U2 is the low-level voltage connected to the sensing terminal of the connector.

[0050] Therefore, the voltage U can be used as a normal reference voltage for the circuit.

[0051] When the first current limiting resistor R1 and / or the connector is open circuited, it is obvious that the voltage signal measured by the second pin P2 of the controller is substantially the same as the high-point level signal output by the power supply component, but is far away from the reference voltage.

[0052] When the parameters of the first current limiting resistor R1 and / or the connector drift, the resistance value of the first current limiting resistor R1 and / or the connector increases or decreases due to temperature and other reasons. When the resistance value of the first current limiting resistor R1 and the connector decreases relative to that in normal circumstances, it is obvious that the voltage signal measured by the second pin P2 of the controller increases relative to the reference voltage; and when the resistance of the first current limiting resistor R1 and the connector increases relative to the resistance value in normal circumstances, the measured voltage signal decreases relative to the reference voltage.

[0053] When a short-circuit fault occurs in capacitor Cs, it is obvious that the capacitor Cs is equivalent to a current-carrying wire with a resistance close to 0, which short-circuits the circuit branch from the second end of the voltage-dividing resistor R3 to the sensing terminal of the connector. At this time, the measured voltage is approximately equal to the low-level voltage signal of the first pin P1 of the controller, and is also far away from the reference voltage.

[0054] Based on the above discussion, it can be determined that under normal circumstances, when the controller is performing a self-test of the capacitive sensor, the controller controls the power supply component and the first current limiting resistor R1 to be connected, and at the same time controls the sensing terminal of the connector to be connected to a low level. When there is no fault in the circuit, the measured voltage signal should be within the reference voltage range. Once the reference voltage is deviated, it means that there is a fault in the circuit of the capacitive sensor.

[0055] Similarly, when the power supply component is connected to the second end of the first current limiting resistor R1 through the voltage divider resistor R3, the same principle can be used to determine that the voltage measured at the second pin P2 of the controller under normal circumstances should also be a reference voltage, but the size of the reference voltage is different from the size of the first end of the first current limiting resistor R1 connected to the power supply component through the voltage divider resistor R3. The specific calculation process of its size can be determined according to the above-mentioned similar calculation process combined with circuit common sense, which is not described in detail in this application.

[0056] In addition, it should be noted that the main function of the voltage-dividing resistor R3 is voltage division. For example, when the power supply component is connected to the capacitor Cs through the voltage-dividing resistor R3, if the capacitor Cs is short-circuited, the voltage-dividing resistor R3 can avoid the problem of excessive instantaneous current causing the controller to burn out.

[0057] However, in the embodiment in which the power supply component is connected to the second end of the first current limiting resistor R1, the first current limiting resistor R1 also plays a voltage dividing role to a certain extent. For this reason, when the power supply component is connected to the second end of the first current limiting resistor R1, the voltage dividing resistor R3 may not be set between the power supply component and the first current limiting resistor.

[0058] Regarding the controller controlling the connection and disconnection between the power supply component and the first current limiting resistor 41, it is possible to consider setting a switch between the first current limiting component 41 and the power supply component, the switch being controlled to open and close by the controller. Similarly, the low-level voltage that is connected and disconnected by the sensing terminal of the connector can also be achieved by setting a switch between the sensing terminal and the low-level signal terminal of the connector.

[0059] Therefore, in an optional embodiment of the present application, the power supply component may include:

[0060] A power supply and a first power switch K1, wherein the high level output end of the power supply is connected to a first current limiting resistor R1 via the first power switch K1; and a controller is used for disconnecting and connecting the first power switch K1.

[0061] The first power switch K1 may be arranged between the power supply and the voltage-dividing resistor R3, or between the voltage-dividing resistor R3 and the first current-limiting resistor R1, which is not specifically limited in the present application.

[0062] In another optional embodiment of the present application, the power supply component also includes a second power supply switch K2, which is used to connect the low-level output end of the power supply and the sensing terminal of the connector; the controller is used to synchronously control the disconnection and connection of the first power supply switch K1 and the second power supply switch K2.

[0063] The power supply generally includes a positive output terminal and a negative output terminal. In this embodiment, the positive output terminal of the power supply is also a high-level output terminal, and the negative output terminal is also a low-level output terminal.

[0064] Of course, in actual applications, the sensing terminal of the connector is not necessarily connected to the negative pole of the power supply, but can also be connected to the ground terminal through the second power supply switch K2, or can also be connected to the connected sensing terminal through a pin of the controller. The controller can also achieve the technical solution of the present application by controlling the output of a low-level signal through the pin. There are other similar methods of connecting the sensing terminal of the connector to a circuit device that can output a low level through the second power supply switch K2 to achieve the technical solution of the present application, which are not listed one by one in the present application.

[0065] In another optional embodiment of the present application, the power supply component is a built-in power supply device of the controller, and is connected to the first current limiting resistor R1 through the third pin P3 of the controller. The controller is used to control the third pin 3 to output a high level signal when the fault self-check is started.

[0066] Generally, the controller chip can output electrical signals through its connection pins. In this embodiment, considering the problem of simplifying the structure of circuit elements, this characteristic of the controller is directly utilized to output a high-level signal through the third pin P3 of the controller.

[0067] Similarly, the sensing terminal of the connector may also be connected to the fourth pin P4 of the controller, so as to output a low level signal through the fourth pin P4 when the fault self-check is started.

[0068] It should be noted that, for the embodiments in which a high-level signal and a low-level signal are respectively output directly through the third pin P3 and the fourth pin P4 of the controller, when the capacitive sensor does not perform self-test fault detection, the controller should control the third pin P3 and the fourth pin P4 to be in a high-impedance state. Specifically, the third pin P3 and the fourth pin P4 can be set to a state of collecting signals to avoid affecting the normal working process of the capacitive sensor.

[0069] Furthermore, in another optional embodiment of the present application, a second current limiting resistor R4 may be provided between the sensing terminal and the low-level output terminal of the connector.

[0070] For the embodiment in which the sensing terminal of the connector is connected to the low-level signal through the second power switch K2, the second current-limiting resistor R4 can be arranged between the second power switch K2 and the sensing terminal of the connector.

[0071] For the embodiment in which the sensing terminal of the connector is directly connected to the fourth pin P4 of the controller, the second current limiting resistor R4 should be arranged between the sensing terminal of the connector and the fourth pin P4 of the controller.

[0072] To summarize, in the present application, a power supply component is added to the circuit of a conventional capacitive sensor to form two different circuit branches, and the connection and disconnection of the power supply component and the circuit of the capacitive sensor are controlled to realize the start and contact of the self-test process. During the self-test process, the voltage value of the branch node in the circuit is detected to determine whether the circuit has a fault. The entire circuit structure is simple and the control process is simple, which is conducive to low-cost and rapid detection of circuit faults of capacitive sensors and is conducive to the widespread application of capacitive sensors.

[0073] The present application also provides an embodiment of a circuit fault self-detection method for a capacitive sensor, and the circuit fault self-detection method for a capacitive sensor is applied to the capacitive sensor as described in any one of the above items. Figure 3 , Figure 3 A schematic flow chart of a circuit fault self-detection method for a capacitive sensor provided in an embodiment of the present application. The method may include:

[0074] S11: Preliminarily output low-level signals through the first pin and the second pin of the controller, respectively, so that the capacitor voltage corresponding to the capacitor reaches a stable state.

[0075] S12: Control the power supply component to connect a high level signal to the first current limiting resistor, and control the sensing terminal of the connector to connect a low level signal.

[0076] S13: Switching the second pin of the controller to a state of collecting voltage signals, so as to collect the electrical signal of the first end or the second end of the first current limiting resistor.

[0077] S14: Determine whether the magnitude of the electrical signal is within a preset voltage range; if not, there is a circuit fault.

[0078] Based on the above discussion, the range of the preset voltage value can be a voltage range within a certain range around the above reference voltage.

[0079] When the voltage signal is less than the first preset voltage value, the capacitor is short-circuited;

[0080] When the voltage signal is greater than the first preset voltage value and less than the minimum normal voltage value, or the voltage signal is greater than the maximum normal voltage value and less than the second preset voltage value, there is a circuit element parameter drift; wherein the voltage range between the minimum normal voltage value and the maximum normal voltage value is the normal voltage range;

[0081] When the voltage signal is greater than the second preset voltage signal value, a circuit break fault exists.

[0082] Generally, the first preset voltage value should be close to 0 or close to the voltage corresponding to the low-level signal output by the first pin of the controller; and the second preset voltage signal should be close to the voltage of the high-level signal output by the power supply.

[0083] For a capacitive sensor that outputs a high-level signal and a low-level signal respectively through the third pin and the fourth pin of the controller when performing fault self-test, the third pin and the fourth pin of the controller should be switched to the receiving pin state at the same time after the self-test is completed so that the capacitive sensor can work normally.

[0084] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. Moreover, the term "include", "comprise" or any other variant thereof is intended to cover non-exclusive inclusion, so that the process, method, article or equipment that includes a series of elements are inherent to the elements. In the absence of more restrictions, the elements limited by the sentence "comprise one..." do not exclude the presence of other identical elements in the process, method, article or equipment that includes the elements. In addition, the above-mentioned technical solution provided in the embodiment of the present application is consistent with the corresponding technical solution in the prior art in principle, and the part is not described in detail, so as not to repeat too much.

[0085] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core ideas of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A capacitive sensor, characterized in that: include: A controller, and a capacitor, a first current-limiting resistor, a connector, and a sensing electrode connected in series with a first pin of the controller; A first end where the first current limiting resistor and the capacitor are connected is connected to a second pin of the controller; It also includes a power supply component and a voltage-dividing resistor, wherein the high-level output end of the power supply component is used to connect to the first end or the second end of the first current-limiting resistor through the voltage-dividing resistor; When the touch-sensitive screen is touched and pressed, the voltage difference between the two conductive layers changes, and an electrical signal corresponding to the changed voltage difference is transmitted to the controller through the sensing electrode in sequence through the connector and the first current-limiting resistor; The controller is used to determine the touch operation according to the collected electrical signal; The controller is used for, when starting the fault self-check, setting the first pin connected to the capacitor to a low level state, controlling the connection between the power supply component and the first current limiting resistor, controlling the sensing terminal connected to the connector and the sensing electrode to connect to a low level signal, and collecting the electrical signal through the second pin of the controller, so as to determine whether there is a circuit fault according to the size of the electrical signal; Wherein, the electrical signal is a voltage signal; when the voltage signal is less than a first preset voltage value, the capacitor is short-circuited; when the voltage signal is greater than the first preset voltage value and less than a minimum normal voltage value, or the voltage signal is greater than a maximum normal voltage value and less than a second preset voltage value, there is a circuit element parameter drift; wherein the voltage range between the minimum normal voltage value and the maximum normal voltage value is a normal voltage range; when the voltage signal is greater than the second preset voltage value, there is a circuit break fault; The power supply component is a built-in power supply device of the controller, and is connected to the first current limiting resistor through the third pin of the controller. The controller is used to control the third pin to output a high level signal when the fault self-check is started; The fourth pin of the controller is connected to the sensing terminal of the connector, and is used to output a low level signal through the fourth pin when the fault self-check is started.

2. The capacitive sensor according to claim 1, characterized in that A second current limiting resistor is also arranged between the fourth pin of the controller and the connector.

3. A circuit fault self-detection method for a capacitive sensor, characterized in that: A capacitive sensor as claimed in any one of claims 1 to 2, comprising: Preliminarily outputting low-level signals through the first pin and the second pin of the controller respectively, so that the capacitor voltage corresponding to the capacitor reaches a stable state; after determining that the electrical signal is within a preset voltage range, controlling the third pin and the fourth pin of the controller to switch to a receiving pin state, so that the third pin and the fourth pin are in a high-impedance state; Control the power supply component to connect a high level signal to the first current limiting resistor through the voltage dividing resistor, and connect a low level signal to the sensing terminal of the connector; Switch the second pin of the controller to a state of collecting voltage signals, so as to collect the electrical signal of the first end or the second end of the first current limiting resistor; control the third pin to output a high level signal, and the fourth pin to output a low level signal; Determine whether the magnitude of the electrical signal is within a preset voltage range, if not, there is a circuit fault; Determining whether the magnitude of the electrical signal is within a normal voltage range includes: The electrical signal is a voltage signal; When the voltage signal is less than a first preset voltage value, the capacitor is short-circuited; When the voltage signal is greater than the first preset voltage value and less than the minimum normal voltage value, or the voltage signal is greater than the maximum normal voltage value and less than the second preset voltage value, there is a circuit element parameter drift; wherein the voltage range between the minimum normal voltage value and the maximum normal voltage value is the normal voltage range; When the voltage signal is greater than the second preset voltage value, there is a circuit break fault; Also includes: When the touch-sensitive screen is touched and pressed, the voltage difference between the two conductive layers changes, and the electrical signal corresponding to the changed voltage difference is transmitted to the controller through the connector and the first current-limiting resistor in sequence through the sensing electrode; the controller collects the electrical signal and determines the touch operation.

Images