Analysis: the principle of capacitive screen and resistive screen and how to distinguish

With the hot sales of iPhone mobile phones, more and more touch screen mobile phones have appeared around us. In response to the impact of Apple iPhone mobile phones, major mobile phone manufacturers have launched their own brand of touch screen mobile phones. And the screen is getting bigger and bigger, and the function is getting more and more. In the touch screen, the material of the touch screen is divided into two completely different types, namely, capacitive screen mobile phones and resistive screen mobile phones.

How to distinguish between capacitive screen mobile phones and resistive screen mobile phones

Method 1: Capacitive screen mobile phones must support multi-touch. (Since multi-touch requires the support of system software, capacitive screens that do not support multi-touch may still be used.)

PS: Don’t blame your phone for a capacitive screen but why it doesn’t support multi-touch. That’s because multi-touch requires not only hardware support (capacitive screen) but also corresponding system software support (such as iPhone’s system, Google’s Android) System, etc.)

Method 2: The touch pen must be a resistive screen phone. (Of course, some resistive screen phones are not equipped with stylus randomly)

Method 3: The resistive screen mobile phone can be touched with the nail.

Representative mobile phone

Capacitive screen phones: iphone, HTC HD2, Nokia N8, Samsung I9000, Sony Ericsson X10

Resistive screen phones: HTC Diamond2, Nokia N97, Samsung I8000, Sony Ericsson X2

Principle of touch screen: From the perspective of technical principles, the touch screen is a transparent absolute positioning system, so it must have three characteristics:

The first is transparency: the quality of transparent materials will directly affect the visual effect of the touch screen, which is mainly reflected in the reflectivity and clarity of the screen.

The second is the absolute coordinate system: our traditional mouse is a relative positioning system, the positioning only refers to the coordinates of the previous mouse position, while the touch screen needs to be selected wherever it is. This is a relative coordinate system. There is an absolute difference in the nature of coordinates.

The third is detection and positioning: touch screen technology relies on the sensor below the screen, so the positioning principle and the sensor used determine most of the technical indicators of the touch screen, including response speed, reliability, stability and life.

The difference between capacitive screen and resistive screen

Capacitive touch screen working method: The capacitive touch screen uses the electricity of the human body to work. The touch screen consists of a four-layer composite glass screen, and a layer of transparent special metal conductive material is pasted on the surface. When a finger touches the touch screen, 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, 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 information of the touch point by accurately calculating the ratio of these four currents. .

Resistive touch screen touch working method: The screen body of the resistive touch screen is a multilayer composite film, with a layer of glass or plexiglass as the base layer, and the surface is coated with a transparent conductive layer (ITO film), and an outer surface is covered on it Hardened, smooth and scratch-resistant plastic layer. Its inner surface is also coated with a layer of ITO, and there are many small (less than one thousandth of an inch) transparent isolation points between the two conductive layers to separate them. When the finger touches the screen, the two layers of ITO come into contact, the resistance changes, and signals are generated in the X and Y directions. The controller calculates the XY coordinates of the contact point according to the detected resistance changes, and then performs the corresponding according to this coordinate Therefore, this technology must use a hard object to apply force to the screen in order to obtain the touch effect.