Deep analysis of the working principle of resistiv

Deep analysis of the working principle of resistive touch screen
The resistive touch screen is controlled by pressure sensing. The main part of the resistive touch screen is a resistive film screen that fits well with the surface of the display. This is a multi-layer composite film. It takes a layer of glass or hard plastic flat plate as the base layer, and the surface is coated with a layer of transparent oxide metal (transparent conductive resistance) conductive layer.
The resistive touch screen is controlled by pressure sensing. The main part of the resistive touch screen is a resistive film screen that fits well with the surface of the display. It is a multi-layer composite film, which takes a layer of glass or hard plastic flat plate as the base, The surface is coated with a transparent oxide metal (transparent conductive resistance) conductive layer, which is covered with an outer surface hardening and smooth anti friction plastic layer. Its inner surface is also coated with a layer of coating. There are many small (less than 1 / 1000 inch) transparent separation points between them to separate and insulate the two conductive layers.
The most basic principle of resistance technology touch screen: when the finger touches the screen, the two conductive layers will contact at the touch point, the resistance will change, generate signals in X and Y directions, and then send them to the touch screen controller The controller detects this contact and calculates the position of (x, y), and then operates according to the way of simulating the mouse.
The key of resistive touch screen lies in material technology. The commonly used transparent conductive coating materials are:
A. Ito, indium oxide, weak conductor, The characteristic is that when the thickness drops below 1800 angstroms (angstroms = 10-10m), it will suddenly become transparent, and the light transmittance is 80%. If it is thinner, the light transmittance will decrease, and when it reaches 300 angstroms, it will rise to 80%. ITO is the main material used in all resistance technology touch screens and capacitance technology touch screens. In fact, the working surface of resistance and capacitance technology touch screens is ITO coating.
B. Nickel gold coating: the outer conductive layer of the five wire resistance touch screen uses nickel gold coating material with good ductility. Due to frequent touch, the outer conductive layer uses nickel gold material with good ductility in order to prolong the service life, but the process cost is relatively high. Although the nickel gold conductive layer has good ductility, it can only be used as a transparent conductor and is not suitable for the working surface of the resistance touch screen, because it has high conductivity and the metal is not easy to achieve very uniform thickness, so it is not suitable to be used as a voltage distribution layer and can only be used as a probe layer.
Four wire resistance screen
When two transparent metal layers of four wire resistance analog technology work, each layer increases 5V constant voltage: one vertical direction and one horizontal direction. A total of four cables are required. Features: high resolution, high-speed transmission response. Surface hardness treatment to reduce scratch, scratch and anti chemical treatment. With smooth and foggy surface treatment. One time correction, high stability and never drift.
Five wire resistance screen
The base layer of the touch screen with five wire resistance technology adds the voltage fields in both directions to the conductive working surface of the glass through the precision resistance network. We can simply understand that the voltage fields in both directions work time-sharing on the same working surface, while the outer nickel gold conductive layer is only used as a pure conductor, The position of the touch point is measured by time-sharing detection of the x-axis and y-axis voltage values of the inner ITO contact point after touch.
The ITO of the inner layer of the five wire resistance touch screen requires four leads, and the outer layer is only one conductor. There are 5 leads out of the touch screen. Features: high resolution, high-speed transmission response. High surface hardness, reduce scratch, scratch and anti chemical treatment. It can still be used after 30 million times of same point contact. Conductive glass is the medium of substrate. One time correction, high stability and never drift. Five wire resistance touch screen has the disadvantages of high price and high environmental requirements
Limitations of resistance screen
Whether it is a four wire resistance touch screen or a five wire resistance touch screen, they are a working environment completely isolated from the outside world. They are not afraid of dust and water vapor. They can be touched by any object and can be used to write and draw. They are more suitable for limited people in the field of industrial control and in the office. The common disadvantage of resistive touch screen is that the outer layer of composite film is made of plastic material. People who don't know too hard or touch with sharp tools may scratch the whole touch screen and lead to scrapping. However, within the limit, the scratch will only damage the outer conductive layer. The scratch of the outer conductive layer has nothing to do with the five wire resistance touch screen, but is fatal to the four wire resistance touch screen.