Knowledge

Disadvantages of capacitive touch screen



Capacitive touch screen transmittance and clarity is better than four-wire resistive screen, of course, and can not be compared with the surface acoustic wave screen and five-wire resistive screen.

Capacitive screen reflective serious, moreover, the capacitive technology of the four-layer composite touch screen for each wavelength of light transmittance is uneven, there is the problem of color distortion, due to light in the reflection between the layers, but also cause the image character blur.

Current: Capacitive screen on the principle of the human body as a capacitor element of the use of an electrode, when there is a conductor close to the sandwich Ito working face coupled with sufficient capacitance, the flow of current is sufficient to cause the capacitive screen error action. Although the capacitance value is inversely proportional to the distance between the poles, it is in direct proportion to the relative area and is also related to the dielectric coefficient. Therefore, when the large area of the palm or hand-held conductors near the capacitive screen and not touch can cause the wrong action of the capacitive screen, in humid weather, this situation is particularly serious, hand-held display, palm close to the monitor 7 cm or the body close to the monitor within 15 centimeters can cause the wrong action of the capacitive screen.

Another disadvantage of the capacitive screen is that there is no reaction when touching with a gloved hand or holding a non-conductive object because of the addition of more insulating media. Drift: Capacitive screen The main disadvantage is the drift: when the ambient temperature, humidity changes, the environmental electric field changes, will cause the drift of the capacitive screen, resulting in inaccurate. For example: The display temperature rise after the boot will cause drift: the user touch the screen while the other hand or side of the body near the monitor will drift; capacitive touch screen near the larger objects will drift, the user touch if someone around to watch will also cause drift; the drift of capacitive screen is a technical deficiency,

Although the environmental potential surface (including the user's body) is far away from the capacitive touch screen, it is much larger than the finger area, and they directly affect the measurement of the touch position. Other: In addition, theoretically many of the relationships that should be linear are actually non-linear, such as: the total amount of electricity flow is different for people with different weights or different levels of wet fingers, and the change of total electrical flow and the change of four separate flow is a nonlinear relationship, Capacitive touch screen used in this four-corner of the custom polar coordinate system does not have the origin of the coordinates, after the drift controller can not detect and recover, and, after 4 A/d is completed, the value of four points to the touch point in the Cartesian coordinate system of the x, Y coordinate value of the calculation process is complex. Since there is no origin, the drift of the capacitive screen is cumulative and calibration is often required on the job site. Capacitive touch screen The most outside of the silica protection glass scratch resistance is very good, but afraid of nails or hard objects, tapping a small hole will hurt the sandwich Ito, whether it is injured and laminated ito or the installation of the transport process of slander and the inner surface ITO layer, capacitive screen will not work properly.