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Capacitance Screen Protective Film
- Jan 03, 2019 -

Special protective film for capacitive screen


Capacitance screen is a four-layer composite glass screen. The inner surface and sandwich of the glass screen are coated with ITO. The outer layer is only 0.0015mm thick silica glass protective layer. The sandwich ITO coating is used as working face. Four electrodes are drawn from four corners, and the inner ITO layer is used as screen layer to ensure working environment.


principle


When the user touches the capacitive screen, because of the electric field of the human body, the user's finger and the working surface form a coupling capacitance. Because of the high frequency signal on the working surface, the finger absorbs a small current, which flows from the electrodes on the four corners of the screen respectively. In theory, the current flowing through the four electrodes is proportional to the distance from the finger to the four corners. The controller passes through the four corners. The precise calculation of the current ratio can get the position.


Main characteristics


Texture of material


Complete scratch-proof glass material (Moorish hardness 7H), not easy to be scratched and worn by sharp objects, not affected by common sources of pollution, such as water, fire, radiation, static electricity, dust or oil pollution. It has the eye protection function of goggles.


sensitivity


A force of less than two ounces can be sensed and a quick response of less than three MS can be obtained.


Accuracy


99% accuracy.


Definition


Three kinds of surface treatment (Polish, Etch, Industrial) are available. The MTBF of SMT controller is greater than 572,600 hours (per MILHANDBOK-217-F1).


Touch life


Any point can withstand more than 50 million touches, and the cursor does not drift after one correction.

Therefore, it can be known that the sensing principle of capacitive screen is not temperature, but the trigger pressure of conductive objects, so the effect of the film on its sensitivity is negligible, but attention should be paid to the special film. It is usually difficult to replace the film (without lifting it)


Note appended:


There are two kinds of capacitive screens on the market at present: glass substrate and plastic substrate. The iPhone uses glass substrate, so it can be easily controlled by touching. This kind of film will not affect any performance. Another kind is plastic substrate, which may affect the touch sensitivity. This has a great relationship with the material.


Resistance screen: Resistance screen is operated by clicking and pressing, that is to say, the screen feels the pressure of your finger or stylus, and then accepts the operation. It's about putting pressure on the screen, which generates an electric current and creates a touch.


Capacitance screen: Capacitance screen is operated by electrostatic induction, that is, the screen feels the static electricity of your finger, and then accepts the operation. Touch sensitive, do not press the screen, support multi-touch, but can only be touched with fingers, the relative accuracy is not very high.


Generally speaking, resistance screens can achieve more accurate positioning, you can operate through fingers or stylus; while capacitance screens can only be operated through electrostatic fingers, pens are not available, if people OVER, then fingers are no longer used. (Of course, there are also pens for capacitive screens, but they are not very easy to use.)


The difference between the two is that the capacitive screen uses a finger touch screen without a handwriting pen (there are also special handwriting pens suitable for the capacitive screen), while the resistive screen needs a handwriting pen or other sharp objects to complete the operation. For example, when you get your mobile phone, you touch the screen with your nails or hard objects. As long as you can operate it, it's a resistive screen, and vice versa, a capacitive screen. In the sunlight, the visual effect of capacitive screen is better than that of resistive screen. Capacitance touch screen is easy to realize multi-touch function (emphasis). Resistance screen is point touch, often with touch pen, low sensitivity, and capacitance screen is surface touch.

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