Capacitive multi-touch screen: definition and features
The screens of modern devices can not only display an image, but also allow you to interact with the device through sensors.
Initially, touch screens were used in some pocket computers, but today touch screens are widely used in mobile devices Smart Film Thailand, players, photo and video cameras, information kiosks, and so on. At the same time, each of the listed devices can use one or another type of touch screen. Currently, several types of touch panels have been developed, and, accordingly, each of them has its own advantages and disadvantages. In this article, what types of touch screens is just considered, their advantages and disadvantages, which type of touch screen is better.
There are four main types of touchscreens: resistive, capacitive, surface-acoustic, and infrared. In mobile devices, only two are most widespread: resistive and capacitive. Their main difference is the fact that resistive screens recognize pressing, and capacitive ones – touch.
Resistive touch screens
This technology is most widespread among mobile devices, due to the simplicity of the technology and low production costs. A resistive screen is an LCD display on which two transparent plates are superimposed, separated by a dielectric layer. The upper plate is flexible film กระจก, as the user presses on it, while the lower one is rigidly fixed to the screen. Conductors are applied to the surfaces facing each other.
The microcontroller applies voltage in series to the electrodes of the top and bottom plates. When the screen is pressed, the flexible top layer bends and its inner conductive surface touches the bottom conductive layer, thereby changing the resistance of the entire system. The change in resistance is recorded by the microcontroller and thus the coordinates of the touch point are determined.
The advantages of resistive screens include simplicity and low cost, good sensitivity, as well as the ability to press the screen with your finger or any object. Of the minuses, it is necessary to note poor light transmission (as a result, you have to use a brighter backlight), poor support for multiple clicks (multi touch screen impact), they cannot determine the pressing force, as well as rather rapid mechanical wear, although in comparison with the life of the phone, this drawback is not so important, as the phone usually fails faster than the touchscreen.
Infrared touch screens
The design and operation of infrared touch screens is quite simple. Along the two adjacent sides of the touchscreen are leds that emit infrared rays. And on the opposite side of the screen are phototransistors that receive infrared rays. Thus, the entire screen is covered with an invisible grid of intersecting infrared rays, and if you touch the screen with your finger, the rays overlap and do not hit the phototransistors, which is immediately registered by the controller, and thus the coordinates of the touch are determined.
In simple terms, avoiding wise technical terms and phrases, a resistive touch screen is a flexible transparent membrane, on which a conductive (in other words, resistive) coating is applied. Under the membrane is glass, also covered with a conductive layer. The principle of operation of a resistive screen is that when you press the screen with your finger or stylus, the glass closes.