Capacitive touchscreens enable touch operations based on the principle of sensing human body current. Their core structure typically consists of four layers of composite glass: the inner surface of the glass substrate and the interlayer are both coated with an ITO (indium tin oxide) conductive layer, while the outermost layer is covered with a high-hardness silica glass protective layer.
When touched, the human body's electric field forms a coupling capacitance with the screen surface, drawing a minute current from the contact point. This current flows out through electrodes positioned at the screen's four corners, with each electrode's current intensity proportional to the distance from the contact point to the electrode. By precisely calculating the ratio of these four currents, the controller determines the touch location.
Regarding outer screen materials, capacitive screens commonly employ specially treated tempered glass. This glass offers excellent light transmission, high strength, a smooth surface, and resistance to pressure, drops, scratches, and impacts. The outer silica glass protective layer exceeds the hardness of most metals, further enhancing scratch resistance. Tempered glass undergoes surface pre-stressing to increase overall mechanical strength and reduce breakage probability.
With technological advancements, capacitive screens have evolved into multiple structural configurations, including common types such as:
G+F Structure: Combines a glass cover plate with a film sensor, offering excellent strength, light transmission, and touch functionality.
G+F+F Structure: Adds an additional film layer to the G+F base, enabling multi-touch capabilities at a correspondingly higher cost.
G+G Structure: Combines a glass cover plate with a glass sensor, offering high hardness, corrosion resistance, excellent light transmission, and smooth touch responsiveness. Surface hardness can exceed 8H.
G+P Structure: Features a PC cover plate paired with a glass sensor. This configuration is low-cost and simple to manufacture but exhibits inferior wear resistance, light transmission, and touch feel.
Glass cover plates offer advantages such as high sensitivity, excellent light transmission, multi-touch support, and robust durability. However, limitations include inherent fragility, relatively high manufacturing costs, and potential performance degradation under extreme temperature/humidity conditions.
PC cover plates provide benefits like low cost, superior toughness, resistance to shattering, and generally better drop resistance than glass. However, they also have limitations, such as low surface hardness and susceptibility to scratches. Their clarity and transparency are inferior to glass, affecting display quality. Touch and swipe interactions may feel less smooth due to higher resistance. Prolonged use can cause yellowing, impacting appearance and light transmission.
The choice of protective layer material ultimately depends on customer requirements and application environments. If you're unsure which option to select, feel free to contact us.