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How to select a high quality capacitive touch screen?

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Update time : 2017-07-08 14:06:01

Capacitive touch screen performance of the most far-reaching changes in technology to be transferred from resistance to capacitive touch screen technology. Forecast according to the market research agency iSuppli, by 2011, nearly 25% of the touch screen mobile phone will be transferred to the resistive capacitive touch screen. Capacitive touch screen technology brings a variety of benefits, will prompt the rapid growth of the market.


When the traditional resistive touch panel is used for sensing the finger or the touch pen, the top layer flexible transparent material is pressed down to contact the conductive material layer below. In fact, the projected capacitive sensing hardware includes the top layer of the glass material, followed by the X and Y axis components, as well as on the glass substrate of indium tin oxide (ITO) insulation layer. Part of the sensor suppliers do a single sensor, embedded X and Y axis sensor and small bridge component in a single ITO, when a finger or other conductive objects close to the screen, it will generate a capacitance between the sensor and the finger. Relative to the system, this capacitor is quite small, but can use a variety of techniques to measure the capacitance.

One technique is the use of TrueTouch components, including the rapid change of capacitance, and the use of a discharge resistor to measure the discharge time. The all glass touch surface gives the user a smooth, smooth touch. End product manufacturers also prefer glass screen, because the glass material will allow the terminal product has a beautiful line of industrial design sense, and can provide high-quality capacitive touch signal measurement. Finally, not only to consider the appearance of the touch panel, it is important to understand the mode of operation. In order to design a good touch screen products, we must pay attention to the following parameters.

 

Accuracy: the accuracy can be defined as the maximum positioning error in a predefined touch screen area, in the linear distance between the actual position of the finger and the measuring position. In the measurement accuracy, the use of a simulation or mechanical fingers. Place the finger on an accurate position on the panel, and then compare the actual position of the finger with the measuring position. Accuracy is very important, the user wants the system to accurately locate the finger position. One of the most important disadvantages of resistive touch screen is low accuracy, and the accuracy will gradually weaken over time. The accuracy of the capacitive touch screen creates many new applications, such as the virtual keyboard and handwriting recognition without touch pen. Figure 1 shows an incomplete structure of the touch panel data, showing the location of the finger position of the phenomenon, but in fact the simulation of the finger is a straight line movement.