The defect of the capacitive touch screen - Hitec

The light transmittance and clarity of the capacitive contact screen are better than those of the four-wire resistive screen, and of course it cannot be compared with the external acoustic wave screen and the five-wire resistive screen.

The defect of the capacitive touch screen - Hitec

The defect of the capacitive touch screen - Hitec

The reflection of the capacitive screen is severe, and the transmittance of the four-layer composite contact screen of the capacitive skill to each wavelength of light is uneven, and there is the problem of color distortion, because the reflection of light between the layers also forms the ambiguity of the image characters. In principle, the capacitive screen uses the human body as an electrode of a capacitor element, and when the conductor is close to the capacitance that meets the capacitance value of the interlayer ITO working surface, the current flowing away will meet the malfunction of the capacitive screen.

We know that the capacitance value, although inversely proportional to the interval between the poles, is proportional to the relative area and is also related to the insulation coefficient of the dielectric. Therefore, when a large area of the palm or the hand-held conductor is close to the capacitive screen instead of contacting, it can cause the malfunction of the capacitive screen, especially in wet weather, the hand holding the monitor, the palm is close to the display within 7 cm or the body is close to the display within 15 cm can cause the malfunction of the capacitive screen. Another defect of capacitive screens is that they do not react when touched by gloved hands or hand-held non-conductive objects, due to the addition of a more insulating medium.

The more important defect of the capacitive screen is drift: when the ambient temperature and humidity are changed, and the ambient electric field is changed, it will cause the drift of the capacitive screen, which is inaccurate. For example, when the temperature of the display rises after powering on, the temperature of the display will drift: when the user touches the screen, the other hand or side of the body approaches the display. The capacitive contact screen drifts back after moving near a large object, and if someone comes around to watch it during contact, it will also cause drift; The drift of the capacitive screen is due to the inherent deficiency of skills, and the ambient potential surface (including the user's body) is much larger than the finger area although it is far away from the capacitive contact screen, which directly affects the determination of the contact position.

In addition, theoretically many relationships that should be linear are actually true and false linear, such as: the total amount of current sucked by people with different weights or different degrees of finger wetness is different, and the change of total current and the change of four sub-currents are linear between right and wrong, the custom polar coordinate system of the four corners used by the capacitive contact screen has no origin on the coordinates, and the controller can not detect and recover after drifting, and after the completion of 4 A/D, the value of the four shunt flows to the X, The process of calculating the Y coordinate value is complex. Because there is no origin, the drift of the capacitive screen is cumulative, and calibration is often required on the job site. The scratch resistance of the outermost silica maintenance glass of the capacitive contact screen is very good, but it is afraid of the knocking of nails or hard objects, and knocking out a small hole will hurt the ITO of the interlayer, whether it is injuring the interlayer ITO or injuring the internal and external ITO layers during the transportation of the device, the capacitive screen will not work normally.

The defect of the capacitive touch screen - Hitec

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