Capacitive touch screens are a common input device that enables interactive operation by detecting capacitance changes in the user's fingers or other objects. Before understanding the detection and verification process of capacitive touch screen, we first introduce the basic principle of capacitive touch screen.
Capacitive touch screens work on the principle of capacitors. A touch screen usually consists of a transparent conductive film (such as an ITO electrode) and a glass or plastic substrate. When no object touches the touch screen, the charge on the conductive film is evenly distributed. When an object (such as a finger) touches the touch screen, the capacitance between the object and the conductive film changes. The sensor detects this capacitance change and converts it into the corresponding position information to enable touch operation.
Capacitive touch screen detection principle:
The detection process of capacitive touch screen can be divided into two stages: electrostatic detection and capacitance detection.
Electrostatic detection: In the idle state of the touch screen, the charge distribution on the conductive film is uniform. The system continuously detects electrostatic signals in various areas of the capacitor screen and establishes a reference value. This reference value is used for subsequent capacitance testing.
Capacitance detection: When an object (such as a finger) touches the touch screen, a capacitor is formed between the object and the conductive film. The touch screen controller sends a series of electrical signals to the conductive film and detects changes in capacitance. By analyzing the pattern and amplitude differences in capacitance changes, the system can determine the position, number and action of the touch.
Verification process of capacitive touch screen:
In order to ensure the quality and reliability of capacitive touch screens, they need to be verified during the production process.
a. Basic function verification: Verify the basic functions of the capacitive touch screen, including the positioning accuracy of touch points and the fluency of action tracking. By moving your finger or pen on the touch screen, check whether you can accurately track the movement of your finger or pen.
b. Sensitivity test: Test the sensitivity of the touch screen, that is, the response ability to light touch. Check whether the touch screen can accurately recognize and respond by using different degrees of light touch or light sweep action. At the same time, it is also necessary to verify the sensitivity performance of the touch screen in different positions and angles.
c. Multi-touch test: For the touch screen that supports multi-touch function, multi-touch test is also required. With multiple locations on the touch screen simultaneously or continuously, check that the touch screen is able to accurately detect and track multiple touch points and map them correctly to the corresponding location on the screen.
d. Noise test: The touch screen may be interfered by external electromagnetic noise when working, resulting in performance degradation. Therefore, it is necessary to conduct noise tests to check the performance of the touch screen in different noise environments. This includes evaluating the anti-interference performance of the touch screen, and whether the touch screen can maintain good stability and reliability in a high-noise environment.
e. Aging test: To verify the long-term performance of the touch screen, perform an aging test. Check whether the touch screen continues to work properly by continuously running a large number of touch operations. This can help evaluate the reliability, durability and stability of the touch screen.
The above is a brief description of the detection and verification of capacitive touch screen. Through these testing and verification processes, it can be ensured that the capacitive touch screen can provide an accurate, reliable and stable touch operation experience in production and use to meet the needs and expectations of users.