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Four common touch screens

1 resistive touch screen

  Resistive touch screen, the screen body is a multi-layer composite film, from a layer of glass or organic glass as the base, the surface is coated with a layer of transparent conductive layer (ITO), which is covered with a layer of outer surface after hardening, smooth scratch resistant plastic layer. The inner surface is also coated with a layer of ITO, and the two layer of the conductive layer has a number of small (less than 1/1000 inch) transparent isolation points to separate them. When the finger touch screen, the two layer ITO contact, the resistance changes, the controller according to the detected resistance changes to calculate the coordinates of the contact points, and then in accordance with the coordinates of the corresponding operation. Resistance screen according to the number of lead wire, divided into four lines, five lines, etc.. The outer surface of the five wire resistive touch screen is a conductive glass, not a conductive coating layer, which has a long life and high transmittance. If the ITO coating of the resistive touch screen is too thin, it is easy to break, and the coating is too thick and will reduce the transparency and reduce the clarity of internal reflection. Due to the often touched, the surface ITO will appear after a certain period of time, small cracks, or even variant, so its service life is not long. Resistive touch screen is cheap and easy to produce, so it is still a popular choice. Four line, five line and seven line, eight line touch screen to make its performance more reliable, but also improve its optical properties.

2 capacitive touch screen

  The capacitive touch screen is coated with a long narrow electrode, which forms a low voltage AC electric field. The touch screen is pasted with a layer of transparent film layer, it is a special kind of metal conductive material. When the user touches the screen capacitor, user fingers and face to form a coupling capacitor. Because of the working face is connected with a high-frequency signal so the fingers will siphon off a small current, the current from the four corners of the screen electrode outflow; and theory through four electrode current and fingers, proportional to the four corners of the distance, the controller through precise calculation of four current ratio can be obtained by the position of contact points. Capacitive touch screen with double glass can not only protect the conductor and the sensor, can effectively prevent the external environmental factors impact on the touch screen, even if the screen is stained with dirt, dust or grease, capacitive touch screen is still able to accurately calculate the touch location. However, due to the different temperature, humidity or grounding conditions, the stability is poor, often will produce drift phenomenon. Although not as widely used as the resistance type, capacitive touch screen is also a popular choice for the selection. This kind of equipment is accurate, fast response, slightly larger size also have higher resolution and more durable (scratch), and is suitable for use as a game of touch screen. Moreover, the new near field imaging technology has improved the performance of capacitive touch screen, and has weakened the drift phenomenon in it and resistive touch screen.

3 infrared touch screen

  Infrared touch screen arrangement of the four sides of the infrared emitting tube and infrared receiving tube, they correspond to horizontal and vertical cross infrared matrix formation. The user on the touch screen, a finger can block after the position of the horizontal and vertical infrared controller through calculation can be used to determine the location of the touch point. Infrared touch screen is also not subject to current, voltage and electrostatic interference, suitable for some harsh environment. Its main advantage is low cost, easy installation, can be used in the different grades of computer. In addition, the response speed is faster than the capacitance, but the resolution is lower due to the absence of the capacitor charge and discharge process.

4 surface acoustic wave touch screen

  The surface acoustic wave is a kind of ultrasonic wave, which is the mechanical energy wave in the medium (such as glass or metal and other rigid materials). The acoustic energy emitted from the surface of the directional and small angle can be achieved by using the wedge shaped base (the wavelength of the surface wave). Surface acoustic wave performance is stable and easy to analyze, and has a very sharp frequency characteristics in the shear wave transmission process, in recent years, in the application of nondestructive testing, contrast and back wave device is developing very fast. The four corners of the touch screen display are equipped with an ultrasonic transmitting transducer and a receiving transducer, which can emit an ultrasonic wave and cover the surface of the screen. When the finger touch screen, because of the absorption of some of the acoustic energy, so that the received waveform changes, that is, a certain time waveform has an attenuation gap, the controller can be calculated based on the attenuation of the signal point position. Surface acoustic wave touch screen is not affected by environmental factors such as temperature, humidity, high resolution, excellent anti scratch resistance, long service life (50 million times without fault), with high light transmittance (92%), can keep clear and transparent image; no drift, only need to install a correction; a third axis (i.e., pressure axis) response, the most suitable for public use. Surface acoustic wave touch screen is easy to be affected by water droplets, dust, the method is to increase the dust, or to increase the monitoring of dirt, accurate identification of the difference between the effective operation and dirt. In addition, because the sound screen can feel the pressure, the invisible increase in the control means, the expansion of the function of the screen is very favorable, and its application range is greatly expanded.

On a：Consumer touch screen

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