We have introduced some information about industrial touch screens before, including choosing products from distinguishing the quality of touch screens, how to maintain industrial touch screens and so on. But how does an industrial touch screen work?
1. Resistive industrial touch screen:
This touch screen uses 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 multi-layer composite film. It uses a glass or hard plastic plate as the base layer, and the surface is coated with a transparent oxide metal conductive layer. It is covered with a layer of hardened outer surface, smooth and anti-scratch 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 points between them to make the two layers conductive the layers are separated by insulation. When the finger touches the stalk of the screen, the two conductive layers are in contact at the touch point, and the resistance changes, generating signals in both X and Y directions, and then sending 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 a mouse. This is the basic principle of resistive technology touch screens.
2. Surface acoustic wave screen:
The three corners of the acoustic wave screen are respectively pasted with transducers that emit and receive sound waves in the X and Y directions (transducers: made of special ceramic materials, which are divided into transmitting transducers and receiving transducers. Energy device. It converts the electrical signal sent by the controller through the touch screen cable into acoustic wave energy and the surface acoustic wave energy converged by the reflection fringe into an electrical signal.), the four sides are engraved with reflection fringes that reflect the surface ultrasonic waves. When a finger or a soft object touches the stalk of the screen, part of the sound wave energy is absorbed, so the received signal is changed, and the X and Y coordinates of the touch are obtained through the processing of the controller.
3. Infrared touch screen:
The infrared touch screen is an infrared matrix densely distributed in the X and Y directions in front of the screen. It detects and locates the user’s touch by continuously scanning whether infrared rays are blocked by objects. As shown in the figure below, this type of touch screen is equipped with an outer frame in front of the display, and a circuit board is designed in the outer frame, so that infrared emitting tubes and infrared receiving tubes are arranged on the four sides of the screen, forming a horizontal and vertical cross infrared matrix in a one-to-one correspondence. After each scan, if all the infrared pairs of tubes are accessible, the green light is on, which means everything is normal.
The advantage of the infrared touch screen is that it can be touched with a finger, a pen or any object that can block light. The disadvantage of the infrared touch screen is that it does not feel good when used on a spherical display. This is because the infrared grating matrix that depends on the work is obviously required to be on the same plane. Therefore, the working plane that really senses touch has a larger distance from the curved display screen. Space, especially at the corners, but this shortcoming does not exist on flat-panel displays, such as liquid crystal displays.
4.Capacitive industrial touch screen:
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, and the outer layer is a thin layer of silica glass protective layer. The interlayer ITO coating is used as the working surface, and the four corners are led out Four electricity, the inner layer 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 capacitors formed between the user and the touch screen surface. 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 electricity on the four corners of the touch screen, and the current flowing through these four electricity is proportional to the distance from the finger to the four corners. The controller obtains the position of the touch point by accurately calculating the ratio of these four currents.
Now the popular capacitive is projected-capacitive touch monitor, which is G+G Layer made by different thickness anti-vandal glass.
Their cover glasses could be anti-vandal from 2mm, 3mm, 4mm, 6mm, 8mm industrial glass.
Also, could be do treatment on anti-glare, anti-reflective.
So, customers would like to use the capacitive touch due to its variability to protect the screen.
After knowing those features on four touch screens, do you have idea on choosing which kind of touch screen for your projects?