Solution to interference problem of capacitive touch screen

#CTP Capacitive touch screen is easy to encounter phenomena such as touch failure, dullness, false touch, and touch drift. These "bad phenomena" are usually caused by the touch principle of the capacitive touch screen. The capacitive touch screen judges the touch operation through the loss of charge on the surface of the #touchscreen and realizes the corresponding functions. If the working environment of the device can cause the flow of charge on the surface of the touch screen for other reasons, it will be judged as an effective touch , The touch screen is not easy to use. Common devices that easily interfere with capacitive touch screens include switching power supplies, motors, and lasers.

Here mainly introduces the method of rectification based on the switching power supply.

Step one

Some of the cheaper switching power supplies on the market will omit the capacitance between the ground wire and the protective ground, so you first need to connect a Y-shaped 2KV capacitor between the ground wire and the 220V/110V protective ground (not the neutral wire). The purpose of this step is to suppress common mode interference.

Step two

 Connect a common mode choke coil in series between VCC and GND that supplies power to the screen, as shown in the figure below. Note that the two wires in the box are short-circuited, and the two sets of wires are connected to VCC and GND respectively, and the positive and negative poles are not distinguished. The choke has a filtering function, which can inhibit the electromagnetic wave generated by the high-speed signal line from radiating outward emission.

Step three

Connect an inductor in series with the VCC line that supplies power to the screen. You can test the effects of the 220 and 100 models, just choose the appropriate one.

other

 In the case of large radiation interference, you can also try to paste the conductive film and ground the conductive film at the same time, which can effectively reduce the interference.

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