What Are the Common Faults of Capacitive Touch Screen?

1. Capacitive touch screen jumping point

Reason analysis: Capacitive touch screens often have jump points, especially in the sample debugging stage, which are mainly caused by electrostatic interference, voltage instability, driver errors, and CTP short circuits.

Solution: Electrostatic interference should be considered in the product design stage, especially the design of FPCA must be grounded. If the customer’s use of environmental interference is serious, an electromagnetic film must be used to resist interference. In addition, the serial port of the CTP and the main control board is not properly connected. If there are problems such as jumping points, the program must be debugged to the best state in the sample debugging stage. The more serious thing is that the CTP itself is short-circuited. This kind of defect is mainly caused by the short of the sensor or FPC. For fatal flaws, the CTP needs to be replaced.

2. Water ripple of capacitive touch screen

Reason analysis: The water ripple of capacitive touch screen is similar to the Newton ring concept of resistive screen. The water ripple of capacitive touch screen is actually a gap between the LCM and CTP, and it is also related to the POL of the liquid crystal module.

Solution: LCM does not have an iron frame. If there is no difference between the POL and the frame, you can consider full lamination. If it is not suitable for full lamination, you can choose frosted POL or increase the distance between LCM and CTP.

3. Capacitive touch screen failure

The fundamental reason for the failure of the capacitive screen is that the current that should flow from the finger does not flow due to the charging of the screen. The current flowing from the reference points in the four corners of the screen cannot be determined from which point, so as long as the charge can be balanced, the screen can be repaired. The following methods are available for reference.

Option One:

1. Turn off the phone, take out the battery, and let the phone sit for about five minutes.

2. Find a USB data cable and try to connect it to the mobile phone.

3. Wash your hands, or get your hands wet (key steps, in order to better export static electricity).

4. In the wet hand state, the thumb of the same hand touches the metal part of the other end of the USB cable, and the index finger is pressed to the ground for about two seconds (preliminary power off).

5. After disassembling the back cover, we can see a small metal block next to the battery compartment. This is the generator of the vibration of the mobile phone, commonly known as the vibrator. Since it is also directly connected to the motherboard of the mobile phone, we can do the same, the thumb of the same hand touches the vibrator in the wet hand state, and the index finger is pressed to the ground for about two seconds.

Option II:

Remove the HD2 battery, turn on the electric iron, press the sheet on the bed sheet, the temperature should be moderate, remove the electric iron, put the HD2 screen upside down on the hot sheet, and iron the screen cover (the temperature should still be moderate, do not repeat ), and so on for about 5 times.

Third solution:

Use a hair dryer to blow the screen, pay attention to turn it on to the mid-range, and blow it evenly to feel the screen is hot.