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What is the industrial touch screen divided into several categories?

29 Jun 2017 -
  Industrial touch screen, with the progress of science and technology, in recent years the development of fast, intelligent interface, through the industrial touch screen will be people and machines as one, changing people's lives and work. Industrial touch screen technology has also experienced from the low-end into the high-end step by step upgrade and development process. It is based on its working principle can be divided into several major categories, what is the difference?

  According to its working principle, its current is generally divided into four categories: resistive touch screen, capacitive touch screen, infrared touch screen and surface acoustic wave touch screen.

First, the resistive touch screen.
  Resistive touch screen part of the screen is a multi-layer composite film, by a layer of glass or plexiglass as a base layer, the surface coated with a layer of transparent conductive layer (ITO film), and then covered with a layer of the outer surface after hardening, Of the plastic layer. Its inner surface is also coated with a layer of ITO, separated by a number of small (less than one thousandth of an inch) of the transparent barrier between the two layers of conductive layers. When the finger touches the screen, the two layers of ITO contact, the resistance changes, the controller according to the detected resistance change to calculate the contact point coordinates, and then follow the coordinates to carry out the corresponding operation. Resistor screen according to the number of leads, divided into four lines, five lines and other types. Five-wire resistance The outer surface of the touch screen is conductive glass rather than conductive coating, this conductive glass life is longer, light transmission rate is also higher.
  If the ITO coating of the resistive touch screen is too thin, it is easy to break, the coating is too thick and will reduce the light transmission and reduce the clarity. As often touched, the surface ITO use a certain time after the emergence of small cracks, or even variants, so its life is not long.
Resistive touch screens are cheap and easy to produce, and are still the most common choice. Four-wire, five-wire and seven-wire, eight-wire touch screen to make its performance more reliable, but also improve its optical properties.

Second, the capacitive touch screen.
  Capacitive touch screen are coated with four sides of the narrow electrode, the internal formation of a low voltage AC electric field. The touch screen is covered with a transparent film layer, it is a special metal conductive material. When the user touches the capacitive screen, the user's finger and the face form a coupling capacitor, because the work surface connected to the high-frequency signal, so the fingers will suck a small current, the current from the screen on the four corners of the electrode And theoretically flowing through the four electrodes of the current and the finger to the four corners of the distance proportional to the controller through the four current ratio of the precise calculation, you can get the contact point position.
  Capacitive touch screen dual glass not only protect the conductor and sensor, more effective to prevent external environmental factors on the touch screen, even if the screen stained with dirt, dust or grease, capacitive touch screen can still accurately calculate the touch position. However, due to the capacitance with temperature, humidity or ground conditions vary, its stability is poor, often produce drift phenomenon.

  Although the resistance is not as wide as the resistive application, capacitive touch screen is also popular for the election type. This type of equipment is accurate, fast response, slightly larger size also has a higher resolution, more durable (scratch-resistant), and thus suitable for use as a game console touch screen. Moreover, the new near-field imaging technology to improve the performance of capacitive touch screen, weakened in its resistive touch screen and the possible drift phenomenon.


Third, the infrared touch screen.
  Infrared touch screen on the four sides of the arrangement of the infrared emission tube and infrared receiver tube, one by one corresponding to the formation of vertical and horizontal cross the infrared matrix. When the user touches the screen, the finger will block the vertical and horizontal two infrared lines, the controller can determine the location of the touch point.
 Infrared touch screen is also not subject to current, voltage and electrostatic interference, suitable for some harsh environments. Its main advantage is the low price, easy installation, can be used in all grades of the computer. In addition, because there is no capacitor charge and discharge process, the response speed faster than the capacitor, but the resolution is low.

Fourth, the surface acoustic wave touch screen.
  The surface acoustic wave is a kind of ultrasonic wave which is a mechanical energy wave propagating in the shallow surface of a medium such as glass or metal. Through the wedge-shaped triangular base (according to the surface wave wavelength strictly designed), can be targeted, small angle surface acoustic energy emission. Surface acoustic wave performance is stable, easy to analyze, and in the process of cross-wave transmission has a very sharp frequency characteristics, in recent years in nondestructive testing, angiography and echoes and other applications in the development of fast.
The touch screen of the four corners of the display are equipped with ultrasonic transmitter and receiver transducers, can send an ultrasound and cover the screen surface. When the finger touches the display screen, due to the absorption of part of the acoustic energy, so that the receiving waveform changes, that is, a time waveform has an attenuation gap, the controller based on the attenuation of the signal can calculate the touch point position.
Surface acoustic wave touch screen from temperature, humidity and other environmental factors, high resolution, excellent scratch resistance, long life (50 million times without failure), high transmittance (92%), to maintain a clear and transparent Image; no drift, only one time to correct the installation; a third axis (ie pressure axis) response, the most suitable for public places.
The surface acoustic wave touch screen is susceptible to water droplets and dust effects. The improved method is to add dustproof strips, or to increase the monitoring of dirt, to accurately identify the difference between effective operation and dirt. In addition, because the sound screen can feel the pressure, virtually increase the control means, the expansion of the screen function is very favorable, and its scope of application and greatly expanded.

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