Analysis of the mainstream technology of touch panel

In recent years, the application of touch panels can be said to be more and more extensive, from the early military or some special applications, to many places have adopted touch panels, if you use Yahoo! Or if Google searches with the touchpanel keyword, it grows with hundreds of results every day. It can be seen that the touch panel is already a popular and fast-growing application and market. However, there are more than four or five types of technology for touch panels and many manufacturers have invested in them. If some customers want to use touch panels, they will be confused by various kinds of information and be at a loss. This article is based on the current mainstream and future technologies, and hopes to provide some useful references for readers who are first involved in touch panels.

Resistive

The resistive touch screen can be said to be the most used technology at present. The resistive driving principle is to find the coordinate axis by means of voltage drop. As can be seen from the figure below, the X axis and the Y axis are each composed of a pair of Driven by a voltage of 0 to 5V, when the resistive touch screen is touched, a voltage drop will occur due to the loop being turned on, and the controller will calculate the proportion of the voltage drop and then further calculate the coordinates axis.

In terms of resistive structure, usually the upper resistive layer is made of ITOCoating PET, and the lower layer is made of ITOCoating PET or glass. When not in use, the upper and lower layers are supported by insulator SpacerDot Open, otherwise there will be problems with ConstantTouch (cursor fixed every point).

FilmonGlass (FG), which is a general resistive structure, that is, the upper layer is ITOCoating PET, and the lower layer is ITOCoating general glass. The disadvantage is that if the general glass is accidentally broken during use, the glass fragments will cut the user.

In order to avoid such accidents, 3M especially adopts a more secure architecture PolyesterLaminated (PL). The upper layer is ITOCoating PET (refer to the figure below), but the lower layer is ITOCoating PET, optical glue, chemically strengthened glass (from top to bottom) under). The chemically strengthened glass is 3.4 times stronger than ordinary glass. When the chemically strengthened glass is broken, optical glue can cover the entire layer of fragments of the chemically strengthened glass to prevent the fragments from cutting the user, just like a car block. Like windshield insulation paper, it can only crack without breaking. The safety of this type of PolyesterLaminated resistive panel is far better than FilmonGlass (FG).

Capacitive

Compared with the resistive type, the capacitive touch panel is a completely different technology. The capacitive structure is relatively simple. Basically, the ITO glass is the main body. The four corners of the ITO glass discharge and form a uniform electric field on the surface. When a conductive object, such as a human finger, draws a small amount of current, the controller behind will calculate the proportion of the current drawn and calculate the X axis and Y axis.

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