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What's The Capacitive Touchscreens Panel Principle?

Capacitive touchscreens Panel Principle

It uses the current induction of the human body to work. The capacitive touchscreens panel is a four-layer composite glass screen. The inner surface of the glass screen and the interlayer are each coated with a layer of ITO. The outermost layer is a thin protective layer of silica glass. The sandwich ITO coating is used as the working surface, and four electrodes are drawn on the four corners. The inner ITO is a shielding layer to ensure a good working environment.

When the finger touches the metal layer, due to the electric field of the human body. The user and the touch screen surface form a coupling capacitor. For high-frequency currents, capacitors are direct conductors. Then the finger draws a small current from the contact point. This current 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 passes the accurate calculation of the proportions of these four currents. Get the location of the touch point.

Defects Of Capacitive touchscreens Panel

The light transmittance and clarity of the capacitive touchscreens panel is better than that of the four-wire resistive screen. Of course, it cannot be compared with surface acoustic wave screens and five-wire resistive screens. The capacitive screen is seriously reflective. Moreover, the four-layer composite touch screen of capacitive technology has uneven light transmittance to light of various wavelengths. There is a problem of color distortion. Because of the reflection of light between layers. It also causes blurring of image characters.

In principle, the capacitive screen uses the human body as an electrode of a capacitor element. When a conductor is close to the working surface of the interlayer ITO, a sufficient amount of capacitance is coupled. The current flowing away is enough to cause malfunction of the capacitive screen. We know that although the capacitance value is inversely proportional to the distance between the poles, it is directly proportional to the relative area. And it is also related to the insulation coefficient of the medium. Therefore, when a large-area palm or a hand-held conductive object approaches the capacitive screen instead of touching it, it can cause the capacitive screen to malfunction. In wet weather, this situation is particularly serious. Hold the monitor with your hand, with the palm of your hand close to the monitor within 7 cm. Or the body is closer than 15 cm to the monitor. Can cause the capacitive screen to malfunction.

The main disadvantage of capacitive screens is drift. When the environmental temperature and humidity change, the environmental electric field changes. Will cause the capacitive screen to drift and cause inaccuracy.