Principle of five-wire resistive screen

Principle of five-wire resistive screen

The advantage of the four-wire resistive touch screen is that it can not only calculate the horizontal X, Y coordinates, but also measure the vertical Z coordinate through a series of methods, that is, the pressure of the finger, which is obtained by measuring the vertical contact resistance Rtouch, because the contact occurs When the contact resistance is inversely proportional to the pressure, the greater the pressure, the smaller the contact resistance. The measured value of this resistance can be used to quantify the contact pressure.

The disadvantage of the four-wire resistive touch screen is that it is not durable enough, and the device will be damaged by pressing and applying pressure for a long time. Because every time it is touched, the upper layer of PET and ITO will be deformed, and the ITO material is brittle and easily damaged when the deformation occurs frequently. Once the ITO layer is broken, the uniformity of conductivity is destroyed, and the proportional equivalence when deriving the coordinates above no longer exists. This kind of breakage can easily occur in areas that are frequently touched, such as the position of the "confirm" button. Another disadvantage is that the ITO attached to the PET movable substrate will not be fully oxidized. Once exposed to a humid or heated environment, the oxidation will cause the resistance to rise, which will also destroy the conductivity uniformity, causing errors in the coordinate calculation, that is, "drift" phenomenon.

This gave birth to the concept of five-wire resistive screen. Five-wire resistive touch screen In view of the shortcomings of the four-wire resistive touch screen, the structure of the five-wire resistive touch screen is that both X and Y electrodes are made on the ITO layer attached to the glass substrate, and the upper ITO is only used as the active electrode. The X and Y electrodes of the bottom layer of ITO lead to UL, UR, LL, LR from the four corners, plus the upper active electrode, so there are five lines in total. The advantage of the five-wire resistive touch screen is that the glass substrate is relatively strong and not easily deformed, and the ITO attached to it can be fully oxidized. The glass material does not absorb water, and its expansion coefficient is very close to that of ITO, and the resulting deformation will not cause ITO damage. The upper layer of ITO is only used as the lead-out electrode, and no current flows. Therefore, uniform conductivity is not required. Even if it is damaged due to deformation, the resistive screen will not "drift".