Resistive touch screens are controlled by pressure sensing. The main part of the resistive touchscreen is a resistive film screen that fits very well with the display surface, a multilayer composite film, which is a layer of glass or hard plastic plate as the base, the surface is coated with a layer of transparent oxide metal conductive layer, which is covered with a layer of surface hardening treatment, a smooth anti-rubbing plastic layer, its inner surface is also coated with a layer of coating, between them a number of small transparent isolation points to separate the two layers of conductive insulation. When the finger touches the screen, the two-layer conductive layer at the touch point position has the contact, the resistance changes, in the X and y two directions to generate signals, and then send the touchscreen controller. The controller detects the contact and calculates the position, and operates according to the simulated mouse. This is the basic principle of resistive technology touching screen. The key of resistive touchscreen is material technology, commonly used transparent conductive coating material:
ITO, indium oxide, weak conductive body, the characteristic is when the thickness drops to 1800, the following will suddenly become transparent, light transmittance of 80%, and then thin down the transmittance of the more than 300, to the thickness of the rise to 80%. Ito is the main material used by all resistive touch screens and capacitive technology to touch screens, in fact, the resistance and capacitive technology touch screen face is ito coating.
Ni-gold coating, five-wire resistance touch screen The outer conductive layer is used in a good ductility of nickel-gold coating materials, external conductive layer due to frequent touch, the use of ductile nickel materials for the purpose of prolonging the service life, but the process is relatively high cost. Although ductile ni-gold conductive layer, but only transparent conductor, not suitable for resistance touch screen as the face, because it is high conductivity, and metal is not easy to achieve a very uniform thickness, not suitable for voltage distribution layer, only as a probe.
Four-wire resistive touch screen
Two-layer transparent metal layer of four-wire resistor analog technology each layer increases 5V constant voltage: a vertical direction, a horizontal direction. A total of four cables are required. Features: High resolution, high speed transmission. Surface hardness treatment, reduce abrasion, scratch and prevention of chemical treatment. With smooth and fog surface treatment. One correction, high stability, never drift.
Five-wire resistive touch screen
Five-wire resistor technology touch screen at the grassroots level of the two directions of the voltage field through the precision resistor network is added to the glass in the conductive face, we can simply understand that the voltage field time-sharing work in two directions is added to the same working face, and the outer nickel-gold conductive layer is only used as a pure conductor, with the method of touching the position of the touch point in detecting the x-axis and y-axis voltage values of the inner Ito contact point.
Five-wire resistive touch screen inner layer Ito need four leads, the outer is only a conductor, touch screen to draw line total 5. Features: High resolution, high speed transmission response. High surface hardness, reduce abrasion, scratch and chemical treatment. Contact with the same point 30 million times is available. Conductive glass is the substrate of the medium. One correction, high stability, never drift. The five-wire resistive touchscreen has a high price and a high demand for the environment.
Limitations of resistive touch screen
Whether it is a four-wire resistive touch screen or five-wire resistive touch screen, they are a totally isolated working environment, not afraid of dust and moisture, it can be used with any object to touch, can be used to write and paint, more suitable for industrial control areas and the use of limited people in the office. The common disadvantage of resistive touch screens is that the outer layer of the composite film is used in plastic materials, not knowing the person too hard or using the sharp touch may scratch the entire touchscreen and lead to scrap. However, within the limits, scratches will only hurt and outside the conductive layer, the outer conductive layer scratches on the five-wire resistive touch screen is not related, but the four-wire resistive touch screen is fatal.