Resistive Touch Screen

The touch screen is a device for entering information, based on the coordinate principle of perception, which reacts to touch. They usually become an alternative to a whole heap of mechanical buttons, which is very convenient, since it allows you to combine the display and the input device. The reliability of the operation of such a system is much higher due to the fact that there are no mechanical and moving parts.

The very first models of touch screens were created in the late sixties of the last century, just then the scientist Samuel Hurst realized that he did not want to read the kilometers of tapes tapes. In 1971, he founded the company Elotouch, which released an emigraph, which was the first computing device that had a resistive touch screen. After a while his company merged with another company called Siemens, after which it became known as Elographics. Thanks to this cooperation, touch panels for the kinescope were developed, which already existed. In 1982, was introduced to the world's first TV, which had a touch panel.

At the moment, touch screens are accepted to be divided into several types, depending on what technology their sensor functions. Resistive touch screen can be four-wire, five-wire or eight-wire. In addition, there are screens capacitive, optical, matrix, strain-gauge, based on infrared rays and on the basis of surface acoustic waves. There are several dozen other patented technologies, however they are not as popular as resistive and capacitive ones. Most of them are inefficient or work on a very outdated technology.

Resistive Touch Screen

This kind of displays today is the most popular. The simplest in terms of implementation at the moment is a four-wire resistive touch screen. It includes a glass panel and a flexible plastic membrane with a thin coating of high conductivity. The space between the membrane and the glass is filled with micro insulators, which reliably protect the surfaces conducting the current. Thin metal plates, called electrodes, are installed at the edges of each layer. In the front layer with a resistive material, they are placed horizontally, and in the rear, vertically, which is designed to effectively calculate the coordinates of the tangency. When a resistive touchscreen is pressed, the panel and membrane are closed, and the resistance at the touch point is recorded by a special sensor, which is converted into a signal. Eight-wire touch screens represent a more advanced technology. While their accuracy is noticeably higher, their reliability and duration of operation are a little "lame".

The five-wire resistive touch screen is significantly more reliable due to the fact that the resistive coating of the membrane has been replaced by a conductive one, which continues to work even when the membrane is damaged. The rear window is covered with a special material with four electrodes on the corners, which are constantly energized. The fifth electrode serves as a terminal for the front layer having conductive properties. At the moment of touching the screen, the upper and lower layers collide, and the controller first of all will register the fact of touch, that is, the change in the front layer. After this, the ground plane of the two horizontal electrodes will first be grounded on the back layer, and then the vertical electrodes are closed.

This description of the functioning of the resistive touch screen is general, but it should be sufficient to understand this technology.