A touch key sensing circuit capable of preventing false triggering

Abstract

The utility model relates to the technical field of response control, specifically touch button response circuit that can prevent false triggering, it contains the main touch capacitor for realizing touch response, the main touch capacitor one end ground, the other end is connected to the power supply anode through resistance five, the main touch capacitor this end still is connected with main amplifier, and is connected on its negative input, the circuit is equipped with the noise reduction capacitor, the noise reduction capacitor rear is connected with shielding drive, shielding drive and main amplifier's output end are connected to the rear differential amplifier, and the differential amplifier rear end is connected with hysteresis comparator, hysteresis comparator output signal, simple structure, and the sensitivity of touch can be adjusted through resistance, and the system flexibility is good, through synchronous electrode potential and differential amplification, filter out noise and electromagnetic interference, ensure that touch signal is clear and accurate, guarantee that the main touch capacitor can accurately detect finger contact, prevent false triggering caused by dust or static electricity etc.

Description

Technical Field

[0001] This utility model relates to the field of sensing control technology, specifically to a touch button sensing circuit that can prevent accidental triggering. Background Technology

[0002] Traditional mechanical buttons are gradually being used less due to aesthetic reasons, while touch buttons have become a common and primary control method in modern electrical appliances. In design and use, accurate touch button sensing is the prerequisite for all functions. In practical applications, touch sensing systems often face various interference sources, such as environmental noise, static electricity, and dust. These external factors can easily cause false triggering of touch buttons, causing the equipment to deviate from the working state set by the user. Utility Model Content

[0003] The purpose of this invention is to address the shortcomings and deficiencies of the existing technology by providing a reasonably designed touch button sensing circuit that can prevent accidental triggering, thereby solving the aforementioned defects.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: It includes a main touch capacitor for realizing touch sensing, one end of the main touch capacitor is grounded, and the other end is connected to the positive power supply through a resistor five. The other end of the main touch capacitor is also connected to a main amplifier and connected to its negative input terminal. The circuit includes a noise reduction capacitor, and a shielded driver is connected after the noise reduction capacitor. The shielded driver and the output terminal of the main amplifier are connected to a differential amplifier. A hysteresis comparator is connected to the rear end of the differential amplifier, and the hysteresis comparator outputs a signal.

[0005] Preferably, the shielding driver is an operational amplifier, the two ends of the noise reduction capacitor are respectively connected to the negative input terminal and the output terminal of the shielding driver, and a resistor is provided between the capacitor and the negative input terminal of the shielding driver. The positive input terminal of the shielding driver is grounded, and the output terminal of the shielding driver is connected to a differential amplifier.

[0006] Preferably, the output terminal of the main amplifier is connected to the positive input terminal of the differential amplifier through resistor three, the output terminal of the shielded driver is connected to the negative input terminal of the differential amplifier through resistor four, and the output terminal of the differential amplifier is connected to its negative input terminal through resistor eight.

[0007] Preferably, the output terminal of the differential amplifier is connected to the positive input terminal of the hysteresis comparator. The circuit also includes a reference Ref. The negative input terminal of the hysteresis comparator is connected to the reference Ref through a resistor. A resistor is also connected between the output terminal and the negative input terminal of the hysteresis comparator.

[0008] Preferably, a resistor is also connected between the main touch capacitor and the main amplifier.

[0009] The beneficial effects of this utility model after adopting the above structure are:

[0010] 1. This application has a simple structure and does not require a main control program. The system can be operated by confirming the resistance value and the reference voltage value during the design. Furthermore, the touch sensitivity can be adjusted by the resistance value, making the system highly flexible.

[0011] 2. This application employs noise-reducing capacitors, shielded drivers, and differential amplifiers. By synchronizing electrode potentials and differential amplification, noise and electromagnetic interference are filtered out to ensure clear and accurate touch signals. This ensures that the main touch capacitor can accurately detect finger contact and prevents false triggering caused by dust or static electricity.

[0012] 3. In this application, a hysteresis comparator is used, which uses delayed feedback and threshold comparison to ensure that the signal is only triggered when it reaches a certain strength, thereby improving stability. Attached Figure Description

[0013] Figure 1 This is the circuit diagram of this utility model.

[0014] Explanation of reference numerals in the attached figures:

[0015] C1, main touch capacitor; C2, noise reduction capacitor;

[0016] R1, Resistor 1; R2, Resistor 2; R3, Resistor 3; R4, Resistor 4; R5, Resistor 5; R6, Resistor 6;

[0017] R7 is a resistor of seven; R8 is a resistor of eight.

[0018] U1, main amplifier; U2, shielded driver; U3, differential amplifier; U4, hysteresis comparator. Detailed Implementation

[0019] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0020] See Figure 1It includes a circular main touch capacitor C1 for touch sensing. One end of the main touch capacitor C1 is grounded, and the other end is connected to the positive power supply (3.3V) through resistor R5. The other end of the main touch capacitor C1 is also connected to the main amplifier U1 through resistor R6 and connected to its negative input terminal. The circuit includes a noise reduction capacitor C2. The shielded driver U2 is connected to the back of the noise reduction capacitor C2. The output terminal of the shielded driver U2 and the main amplifier U1 is connected to the differential amplifier U3. The back end of the differential amplifier U3 is connected to a hysteresis comparator U4, which outputs a signal.

[0021] The shielded driver U2 is an operational amplifier. The two ends of the noise reduction capacitor C2 are connected to the negative input terminal and the output terminal of the shielded driver U2, respectively. A resistor R7 is also provided between C2 and the negative input terminal of the shielded driver U2. The positive input terminal of the shielded driver U2 is grounded, and the output terminal of the shielded driver U2 is connected to the differential amplifier U3.

[0022] The output of the main amplifier U1 is connected to the positive input of the differential amplifier U3 through resistor R3. The output of the shielded driver U2 is connected to the negative input of the differential amplifier U3 through resistor R4. The output of the differential amplifier U3 is connected to its negative input through resistor R8.

[0023] The output of differential amplifier U3 is connected to the positive input of hysteresis comparator U4. The circuit also includes a 1.2V reference Ref. The negative input of hysteresis comparator U4 is connected to the reference Ref through resistor R1. Resistor R2 is also connected between the output and negative input of hysteresis comparator U4.

[0024] The values ​​of resistors R5 and R6 determine the amplitude and impedance of the signal amplification. Therefore, the resistance values ​​are calculated according to actual needs. Resistor R7 is used to provide input impedance, ensure the signal path, ensure the normal operation of shielded driver U2 and form negative feedback. Resistor R1 provides a reference voltage for hysteresis comparator U4. It sets the threshold voltage by forming a voltage divider with resistor R2. In addition, the hysteresis circuit formed by resistors R1 and R2 ensures that hysteresis comparator U4 will only output a stable trigger signal at a certain threshold, thereby avoiding oscillations caused by small noises or signal changes.

[0025] During use, when a finger approaches, the main touch capacitor C1 changes, generating an electrical signal. The main amplifier U1 amplifies the signal from the main touch capacitor C1, while the shielded driver U2 drives the noise reduction capacitor C2. Both sets of output signals are simultaneously input into the differential amplifier U3, which calculates the voltage difference between them to remove common-mode interference and form a differential signal. This signal is then input into the hysteresis comparator U4, which compares it with a reference voltage. The two resistors form a feedback circuit, producing a hysteresis effect. This prevents fluctuations or noise from causing the hysteresis comparator U4 to frequently change its output, ensuring the stability of the trigger signal. If the differential signal exceeds the set threshold, the output of the hysteresis comparator U4 can generate a stable trigger signal to drive the subsequent circuitry.

[0026] In the design, a threshold is generated by adjusting the sensitivity of the main touch capacitor C1 and the gain of the differential amplifier U3. Only a strong and continuous change in capacitance exceeding this threshold can generate a valid signal, reducing false touches. In addition, the resistance values ​​of resistors R1 and R2 can be adjusted according to actual tests to set a higher touch threshold, ensuring that the touch is triggered only when the signal change value exceeds this threshold, thereby preventing false touches caused by dust or static electricity.

[0027] It should be understood that the above-described specific embodiments of this utility model are merely illustrative or explanatory of the principles of this utility model and do not constitute a limitation thereof. Therefore, any modifications, equivalent substitutions, improvements, etc., made without departing from the spirit and scope of this utility model should be included within the protection scope of this utility model. Furthermore, the appended claims are intended to cover all variations and modifications falling within the scope and boundaries of the appended claims, or equivalent forms of such scope and boundaries.

Claims

1. A touch button sensing circuit that prevents accidental triggering, comprising a main touch capacitor (C1) for implementing touch sensing, characterized in that: One end of the main touch capacitor (C1) is grounded, and the other end is connected to the positive power supply through resistor five (R5). The main touch capacitor (C1) is also connected to the main amplifier (U1) at this end, and is connected to its negative input terminal. The circuit includes a noise reduction capacitor (C2), and a shielded driver (U2) is connected after the noise reduction capacitor (C2). The shielded driver (U2) and the output terminal of the main amplifier (U1) are connected to the differential amplifier (U3) at the rear. A hysteresis comparator (U4) is connected at the rear end of the differential amplifier (U3), and the hysteresis comparator (U4) outputs a signal.

2. The touch button sensing circuit for preventing accidental triggering according to claim 1, characterized in that: The shielded driver (U2) is an operational amplifier. The two ends of the noise reduction capacitor (C2) are connected to the negative input terminal and the output terminal of the shielded driver (U2) respectively. A resistor (R7) is also provided between the capacitor and the negative input terminal of the shielded driver (U2). The positive input terminal of the shielded driver (U2) is grounded, and the output terminal of the shielded driver (U2) is connected to the differential amplifier (U3).

3. The touch button sensing circuit for preventing accidental triggering according to claim 2, characterized in that: The output of the main amplifier (U1) is connected to the positive input of the differential amplifier (U3) via resistor three (R3), the output of the shielded driver (U2) is connected to the negative input of the differential amplifier (U3) via resistor four (R4), and the output of the differential amplifier (U3) is connected to its negative input via resistor eight (R8).

4. The touch button sensing circuit for preventing accidental triggering according to claim 3, characterized in that: The output of the differential amplifier (U3) is connected to the positive input of the hysteresis comparator (U4). The circuit also includes a reference Ref. The negative input of the hysteresis comparator (U4) is connected to the reference Ref through resistor one (R1). Resistor two (R2) is also connected between the output of the hysteresis comparator (U4) and the negative input.

5. A touch button sensing circuit to prevent accidental triggering according to claim 1, characterized in that: A resistor (R6) is also connected between the main touch capacitor (C1) and the main amplifier (U1).

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