Industrial tablet PC is a kind of industrial control machine, for the all-in-one machine structure, host, LCD monitor, touch screen set into one. With touch function, sturdy, vibration-proof, wide temperature, rich I/O interface and other characteristics, so that the user and the machine to communicate, convey, input, receive information more convenient and fast, play a role in simplifying the work, improve efficiency, is the best solution for human-machine interface. At present, industrial tablet PC has been widely used in self-service terminals, medical instruments, industrial control, automation equipment, telecommunications, electricity, networks, rail transportation and other fields.
Industrial tablet PC commonly used touch screen capacitive touch screen, resistive touch screen, infrared touch screen, etc., different touch screen using different environments, directional system is also different. Among them, resistive touch screen can be divided into four-wire resistive screen and five-wire resistive screen.
Resistive touch screen is through the principle of pressure sensing to realize the touch control, the physical position of the touch point (X, Y) in the rectangular area will be converted into a voltage on behalf of the X coordinate and Y coordinate. Resistive touch screen is the structure of film plus glass, film and glass adjacent side are coated with ITO (nano indium tin metal oxide) coating, ITO has good conductivity and transparency. When touching the operation, the ITO of the lower layer of the film will contact the ITO of the upper layer of the glass, and the corresponding electrical signals will be transmitted through the sensor, and then sent to the processor through the conversion circuit, and then converted into the X and Y values on the screen through the arithmetic operation, so as to complete the action of point selection and present it on the screen of the industrial tablet PC.
Four-wire resistive screen
Four-wire resistive screen has two layers of ITO working with a constant voltage of 5V added to each layer: one in the vertical direction and one in the horizontal direction.
Five-wire resistive screen
Five-wire resistive screen of the grass-roots level of the two directions of the voltage field through the network are added to the conductive surface of the glass, can be understood as the two directions of the voltage field time-sharing work added to the same surface, and the outer layer of nickel-gold conductive layer is only used only as a pure conductor, there is a touch of time-sharing detection of the inner layer of the ITO contact point of the X-axis and the Y-axis voltage value of the method of measurement of the touch point position. Five-wire resistive touch screen inner ITO need four leads, the outer layer only as a conductor only one, the touch screen has to lead to a total of five lines.
Resistive screen is characterized by high resolution, high-speed transmission response. High surface hardness, reduce scuffs, scratches and anti-chemical treatment, you can use any object to touch, suitable for industrial control field. Once calibrated, high stability, never drift.
Precautions
As the resistance touch screen due to the need for a certain pressure, a long period of time to work is likely to cause wear and tear of the surface material, or the upper and lower layers to lose elasticity and cause poor contact problems occur, thus affecting the normal life cycle of the product. In addition, the outer layer of the resistive screen composite film is made of plastic material, too hard or use a sharp instrument to touch may scratch the whole touch screen and cause the industrial tablet PC can not work. However, within limits, the scratch will only hurt the outer conductive layer, the outer conductive layer of the scratch for the five-wire resistive screen does not matter, while the four-wire resistive screen is affected, so the industrial tablet PC if you use the resistive screen should be used with five-wire resistive screen.