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Capacitive Touch Screen Defect
- May 10, 2018 -

The transmittance and clarity of the capacitive touch screen is better than the four-wire resistive screen, which is not compared with the surface acoustic wave screen and the five-wire resistive screen. Capacitance screen reflection is serious, and the capacitance technology of four layer composite touch screen for each wavelength of light transmittance is not uniform, has the problem of color distortion, due to the reflection light between the layers, also caused the image fuzzy characters.

Current, capacitance screen on the principle of human body as a capacitor element one electrode is used, when there is a close to the conductor and the interlayer coupling between ITO face out enough capacity value of capacitance, escape the current is enough to cause misoperation of capacitive screen.

Although the capacitance value is inversely proportional to the extreme distance, it is proportional to the relative area and is also related to the insulation coefficient of the medium. Therefore, when a large palm or carrying conductor came near the capacitance screen not touch can cause the misoperation of capacitance screen, in the humid weather, this situation is particularly serious, walking live display, palms to display within 7 cm or body to display within 15 cm can cause misoperation of capacitive screen. Another drawback of capacitive screens is that they don't react when they touch a gloved hand or holding a non-conductive object because they add a more insulating medium.

Drift: the main drawback of capacitive screen is drift: when the ambient temperature and humidity change, when the environmental electric field changes, it will cause the drift of the capacitive screen, causing inaccuracy. For example, the temperature rise of the monitor after starting up will cause drift: the user will touch the screen while the other hand or side of the body will drift away from the monitor. The larger object near the capacitive touch screen will drift after moving, and if the user touches it, it will also cause the drift. Capacitive touch drift reason belongs to the congenital deficiency of technical, environmental potential surface (including the user's body) with capacitive touch screen from far away, but is much bigger than the finger area, they directly affect the determination of the touch location.

Many others: in addition, the theory should be linear relationship is actually nonlinear, such as: weight or fingers moist degree different people suck the total power flow is different, and the four of the change of total power flow and the relationship between the change in the flow distribution is nonlinear, capacitive touch screen using the four corners of the custom of polar coordinates is not coordinate origin, after drifting controller cannot detect and recovery, and 4, after the completion of A/D by four shunt amount of value to the touch point on the rectangular coordinate system X, Y coordinates of the complex calculation process. Since there is no origin, the drift of the capacitive screen is cumulative, and calibration is often required at the work site. Capacitive touch screen the outermost silica glass scratch resistant protection is very good, but afraid of fingernail or hard knock, knock out a small hole will hurt interlining ITO, whether hurt interlining ITO or install transportation slander and ITO layer on the inner surface, the capacitance screen can't work normally.

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