LCD touch screen

LCD Touch screen

The two transparent metal layers of the four-wire resistance technology work with a constant voltage of 5V for each layer: one vertical direction and one horizontal direction. A total of four cables are required. Features: High Resolution , high speed transmission response. Surface hardness treatment reduces scratches, scratches and anti-chemical treatment. With smooth and matte finish. One time calibration, high stability, never drifting.

The base layer of the five-wire resistive technology touch screen adds the voltage fields in two directions to the conductive working surface of the glass through the precision resistance network. We can simply understand that the voltage fields in the two directions are applied to the same working surface in a time-sharing manner. The outer nickel-gold conductive layer is only used as a pure conductor, and the position of the touch point is measured by the method of time-sharing detection of the X-axis and Y-axis voltage values of the inner ITO contact point after touch. The five-wire Resistive Touch Screen requires four leads on the inner layer of ITO, and only one conductor on the outer layer. There are 5 lead wires for the Touch Screen.

Resistive Touch screen, using pressure sensing for control. 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 multilayer composite film. It uses a glass or hard plastic plate as the base layer and is coated with a layer of transparent oxide metal (transparent conductive Resistance) conductive layer, covered with a hardened outer surface, smooth and scratch-resistant plastic layer, and its inner surface is also coated with a layer of coating, there are many small (less than 1/1000 inch) transparent isolation between them Point to separate the two conductive layers for insulation. When the finger touches the screen, the two conductive layers are in contact at the touch point, the resistance changes, signals are generated in the X and Y directions, and then sent 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 a mouse. This is the most basic principle of resistive technology Touch Screens. Therefore, the resistive touch screen can be operated with harder objects. The key to resistive touch screens lies in material technology. Commonly used transparent conductive coating materials are: ITO, indium oxide, with a light transmittance of 80%. When it is thinner, the light transmittance will decrease, and it will rise to 80% when the thickness is 300 angstroms. ITO is the main material used in all resistance technology touch screens and capacitive technology touch screens. In fact, the working surface of resistance and capacitance technology touch screens is ITO coating.

Nickel-gold coating, the outer conductive layer of the five-wire resistive touch screen uses a nickel-gold coating material with good ductility. Due to frequent touches, the outer conductive layer uses a nickel-gold material with good ductility. The purpose is to extend 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. It is not suitable for the working surface of the resistive touch screen because of its high conductivity and the metal is not easy to be very uniform in thickness. It is not suitable for the voltage distribution layer and can only be used as a probe. Floor.

The capacitive technology touch screen uses the current induction of the human body to work. The Capacitive Touch Screen is a four-layer composite glass screen. The inner surface and the interlayer of the glass screen are each coated with a layer of ITO. The outermost layer is a thin layer of silica glass protective layer. The interlayer ITO coating is used as the working surface, and the four corners lead out Four electrodes, the inner ITO is a shielding layer to ensure a good working environment. When a finger touches the metal layer, due to the electric field of the human body, a coupling capacitor is formed between the user and the surface of the touch screen. For high-frequency current, the capacitor is a direct conductor, so the finger draws a small current from the contact point. This current flows from the electrodes on the four corners of the touch screen, and the current flowing through these four electrodes is proportional to the distance from the finger to the four corners. The controller calculates the ratio of these four currents to get the touch point position.