The difference between resistive touch screen and capacitive touch screen

The difference between resistive touch screen and capacitive touch screen

Resistive touch screen

Use pressure sensing for control. The main part of the resistive touch screen is a resistive film screen that fits well with the surface of the display. This is a multilayer composite film. It uses a glass or hard plastic plate as the base layer and is coated with a layer of transparent oxide metal (transparent conductive Resistor) conductive layer, covered with a layer of hardened outer surface, smooth and anti-scratch plastic layer, its inner surface is also coated with a layer of coating, there are many small (less than 1/1000 inch) transparent between them The isolation point separates the two conductive layers for insulation. When a finger touches the screen, the two conductive layers are in contact at the touch point, and the resistance changes, and signals are generated in both X and Y directions, and then sent to the touch screen controller . The controller detects this contact and calculates the position of (X, Y), and then operates according to the way of simulating a mouse. This is the most basic principle of resistive technology touch screens.

Resistive screen performance characteristics:

①They are a kind of working environment completely isolated from the outside world, not afraid of dust, moisture and oil.

②It can be touched with any object, can be used for writing and drawing, which is their big advantage

③The accuracy of resistive touch screen only depends on the accuracy of A/D conversion, so it can easily reach 4096*4096•

Capacitive touch screen

The capacitive touch screen uses the current induction of the human body to work. The capacitive touch screen is a four-layer composite glass screen. The inner surface and the interlayer of the glass screen are each coated with a layer of ITO. The outermost layer is a thin layer of silica glass protective layer. The interlayer ITO coating is used as the working surface on the four corners. Lead out four electrodes, the inner ITO is a shielding layer to ensure a good working environment. When a finger touches the metal layer, due to the electric field of the human body, a coupling capacitor is formed between the user and the touch screen surface. For high-frequency current, the capacitor is a direct conductor, so 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 obtains the position of the touch point by accurately calculating the ratio of these four currents. .