Capacitive LCDs consist of a driver electrode and a receiver electrode inside. The driver electrode emits a low-voltage high-frequency signal, which is projected to the receiver electrode to form a stable current. When the human body touches the capacitive screen, the finger forms an equivalent capacitance with the capacitive screen because the human body is grounded.
The high-frequency signal can flow into the ground through this equivalent capacitance, so the amount of charge received at the receiving end is reduced. When the finger is close to the transmitting end, the charge drops more significantly. Finally, the contact point is determined according to the strength of the current received at the receiving end. As for multi-touch, simply put, the screen is divided into blocks. Each area of each group of mutual capacitance module works independently, the capacitive screen can independently detect the touch situation in each area, after processing to achieve multi-touch.
Touch screen ctp (capacitive LCD screen) using the human body current sensor. Capacitive screen is a four-layer composite glass screen. The inner surface and middle layer of the glass screen are coated with ito (nano oxide imprisoned tin). The outer layer is 0.0015 mm thick in response to the protective layer of glass, the middle layer is coated with ito working surface, four electrodes are formed at the four corners, and the inner layer is a shielding layer to ensure the working environment.
When the user touches the capacitive screen, the coupling capacitance is formed between the user's finger and the working surface due to the electric field. Because of the high-frequency signal on the working surface, the finger will absorb a very small current that flows from the electrodes at the four corners of the screen. The current flowing through the four electrodes is theoretically proportional to the distance from the finger to the four corners. The response speed is less than 3 milliseconds, and the accuracy rate is up to 99%.
Capacitive LCD resistive LCD screen and maintenance methods:
1. If you are using a capacitive LCD, it is recommended that the first time you use it, you first install the correct driver for the capacitive LCD, which must meet the specification for the first time, and then click the screen with your finger. Use "/" micro tool touch software "to start" to run the screen calibration program. After calibration is complete, the system will automatically calibrate the data stored in the register controller and restart the system instead of recalibrating according to the screen.
2. When using resistive LCD, if you find that the cursor does not move or can only move in a local area, you can check whether the touch area of the LCD screen is pressed by other touch objects. For example, once the LCD screen is pressed by the display housing or cabinet housing, it means that a point has been touched, so the feedback to the controller's coordinate position is not accurate, the cursor can not be correctly positioned. If the cabinet shell press touch area, you can increase the distance between the cabinet and the display. If the display enclosure presses the touch area, you can try to slightly loosen the screws of the display enclosure.
