Basic technology and classification of touch screens

Basic technology and classification of touch screens

Classification of touch screens
1： In terms of installation methods, touch screens can be divided into external, internal, and integrated types.
External touch screen refers to installing the touch detection device of the touch screen system directly in front of the display device. This type of touch screen is easy to install and very suitable for temporary use. The built-in touch screen is a touch detection device installed inside the housing of the display device, in front of the cathode ray tube. When manufacturing display devices, the touch detection device is made on the cathode ray tube, so that the display device directly has touch function, which is the integrated touch screen.

2： From the perspective of technical principles, touch screens can be divided into five basic types: vector pressure sensing technology touch screens, resistive technology touch screens, capacitive technology touch screens, infrared technology touch screens, and surface acoustic wave technology touch screens.
Among them, the vector pressure sensing technology touch screen has exited the historical stage; Infrared technology touch screens are inexpensive, but their outer frames are fragile and prone to light interference, resulting in distortion on curved surfaces; The design concept of capacitive technology touch screen is reasonable, but its image distortion problem is difficult to fundamentally solve; The positioning of resistive technology touch screens is accurate, but their price is quite high and they are susceptible to scratches and wear; Surface acoustic wave touch screen solves various defects of previous touch screens, with clear and not easily damaged, suitable for various occasions. The disadvantage is that if there are water droplets and dust on the screen surface, the touch screen will become sluggish or even not work. According to the working principle and information transmission medium of touch screens, they are divided into four types: resistive, infrared, capacitive sensing, and surface acoustic wave.

Absolute coordinate system

Touchscreen is an absolute coordinate system, characterized by the fact that the current positioning coordinates are not related to the previous positioning coordinates, and the data of each touch is directly converted to the coordinates on the screen through calibration. In any case, the coordinate system of the touch screen is stable for the output data of the same point. However, it cannot guarantee that every sampling of the same touch point is the same, that is, it cannot guarantee absolute coordinate positioning, which is the so-called drift problem.

location

All kinds of touch screens rely on sensors to work, and some touch screens are even a set of sensors themselves. Their respective positioning principles and the sensors they use determine the response speed, reliability, stability, and lifespan of the touch screen. The technical characteristics of various touch screens are shown in Table 1.