When a finger touches the metal layer, due to the electric field of the human body, the user and the surface of the touch screen form a coupling capacitor. For high-frequency current, the capacitor is a direct conductor. The finger can draw a small current from the contact point. It flows from the electrodes on the four corners of the touch screen, and the current flowing through these four electrodes is proportional to the distance from the finger to the four corners. The controller obtains the position of the touch point by accurately calculating the ratio of these four currents.
The light transmittance and clarity of the capacitive touch screen is better than that of the four-wire resistive screen. Of course, it is not as serious as the surface acoustic wave screen and the five-wire resistive screen. The capacitive touch screen has a four-layer composite touch screen that transmits light at various wavelengths. The rate is not uniform, there is a problem of color distortion, and the reflection of light between layers also causes blurring of image characters.
The main disadvantage of the capacitive screen is drift. When the environmental electric field changes when the ambient temperature and humidity change, it will cause the capacitive screen to drift and cause inaccuracies. The reason for the drift of the capacitive screen is a technical congenital deficiency. Although the environmental potential surface (including the user's body) is far away from the capacitive touch screen, it is much larger than the area of the finger, and they directly affect the determination of the touch position.
The outermost silica protective glass of the capacitive touch screen is very scratch-resistant, but it is afraid of nails or hard objects. Knock out a small hole will damage the interlayer ITO, whether it damages the interlayer ITO or the inner surface ITO layer during installation and transportation, the capacitive screen will not work properly. Touch screens are now widely used in all areas of our lives, and we can all see them in our lives.
