Touch-screen technology used in industrial control application

I. Overview
Industrial touch screen, industrial display by touch even as one of the men and machines of the intelligent interface. It is an alternative to traditional control buttons and indicator lights intelligent operation display terminal. It can be used to set parameters, display data, monitor device status, to curves / animation and other forms depicting automation control process. More convenient, more expressive, and simplify the control program for the PLC, powerful touch screen to create a friendly interface. As a special touch screen computer peripherals, it is the most simple, convenient, a natural human-computer interaction. It gives the media a new look, is a very attractive new multimedia interactive devices.
Second, the principle of industrial touch screen
Touch screen system generally includes a touch screen controller (card) and touch detection device in two parts. Among them, the touch screen controller (card) The main role of the touch point detection device to receive touch information CONTROL ENGINEERING China Copyright, and convert it into contact coordinates, and then sent to CPU, it also can receive commands sent to the CPU and to be implemented: touch detection device is usually installed in front of the display, the main role is to detect the user's touch position and send it to the touch screen control card.
1 Touch Display Module
Resistive touch screen screen body part is a match with the display surface of the multi-layer composite film by a layer of glass or plexiglass as a grass surface is coated with a layer of transparent conductive layer control engineering Copyright, above and then covered with a layer of outer surface hardening treatment, smooth scratch-resistant plastic layer, an inner surface of which is coated with a transparent conductive layer between the two conductive layers are many small (less than one thousandth inch) of the transparent insulating isolation points separate them .
When a finger touches the screen, usually two conductive layers insulated from each other in touch with a contact point, because of which a conductive layer is connected to the Y-axis direction 5V uniform voltage field, making the detection of the voltage from zero to zero, this is detected by the controller on-state after the A / D conversion, and the voltage value obtained can be compared to 5V Y axis coordinates of the touch point, the coordinates of the same reason, the X-axis This resistive touch screen technology is that all the common basic principles. Resistive type touch screen technology is the key material. Lead resistance screen according to number of hours, divided into four or five lines, six lines, multi-wire resistive touch screen. Resistive touch screens in the glass surfaces were painted two OTI transparent conductive metal oxide layer, the outermost layer of OTI as a conductive coating, the second layer precision through OTI is attached to the network anyway in both directions of +5 V to 0V voltage field, OTI between two layers of transparent to small isolated point separated. When a finger touches the screen,OLED Module two conductive layer OTI will be a contact point, the computer detects the voltage and current simultaneously calculate the location of the touch, the reaction speed of 10-20ms.
Five-wire resistive touch screen of the outer conductive layer using good ductility nickel deposit coating materials, the outer conductive layer due to frequent touch, use good ductility nickel deposit materials in order to prolong life, but the technology costs more expensive. Nickel-gold conductive layer scalability is good, but only for transparent conductors, is not suitable as a resistive touch screen face, because it is high conductivity, and the metal is very difficult to achieve a uniform thickness, suitable for voltage distribution layer, only as a probe layer.
Resistive touch screen is a completely isolated from the outside of the work environment, not afraid of dust and water vapor, which can be used to touch any object that can be used to draw and write, more suitable for industrial control and office use. Resistive touch screen is a common drawback is that because the outer layer of the composite film with plastic material, people do not know or use too much force may scratch the whole touch sharp touch screen scrapped as a result. However, within limits,TFT LCD Module only scratch injured outside the conductive layer, the outer layer of conductive scratch for five-wire resistive touch screen is not related, while the four-wire resistive touch screen is fatal.
2 logic control and communication modules
Logic control module contains the 24V DC input (18-32) power, SDRAM memory and CF memory cards, 10/100BaseT Ethernet ports can be used for file transfer, printing and communication with the programmable controller 232 serial port that can be used to connect mouse, keyboard, or print meter USB port. Embedded in the circuit board inside the CPU chip, charge of the display input, output and processing of communication data. Communication module is responsible for a particular network transport, in order to improve the data transfer rate.