the screens touch screen have been gaining more and more space in the market, replacing the old keys, which, a few years ago, were present in all electronic devices.
The term touch screen is translated into Portuguese as touch screen. It is a display electronic device capable of detecting the touch in a certain display area through the pressure exercised on her.
Currently, several devices use this technology, among them, we can highlight cell phones, video games, tablets, bank ATMs, among many others. There are several different types of screens. touch screen, but the main ones are resistive, capacitive, surface acoustic wave and those that use micro cameras instead of sensors.
At screens touch screen with resistive system they are formed by three very thin layers, one resistive and the other of normal glass covered by a layer of conductive metal. The resistive layer is separated from the conductive layer by spacers, and a electric current low intensity passes between these two layers. When you touch the screen, the two layers touch, and the device feels the change in
electric field at that point and sends its coordinates to the computer, which uses a specific program that translates them and transforms the touch into a command.See in the figure how a screen is composed. touch screen with resistive system:
Creating a screen touch screen with resistive system
Due to the way the system perceives the electric field, the pressure change that occurs on the screen can be done by any device. The disadvantage of these screens is that, as they use a metallic plate, even if it is very thin, they only let 75% of the monitor's brightness through.
the screens touch screen with capacitive system they are formed by an electrically charged layer—the capacitive layer—that is placed on top of the monitor panel. When touched, this layer transmits electrons to the finger in a similar way to the electric shock, but with imperceptible intensity. This electrical discharge on the screen is felt by the computer, which calculates the coordinates of the touched point, transforming them into a command for the screen.
The advantage of the capacitive system over the resistive is that it lets through more light, allowing up to 90% of the monitor's light to pass through, resulting in a much clearer image. This technology is used by iPhones and iTouchs.
Screens using the surface acoustic wave system they have two transducers both at the side ends and at the lower and upper ends of the screen, one being a receiver and the other an emitter. Reflectors are also installed on the screen that send an electrical signal from one transducer to another via waves. When the screen is touched, these waves are stopped, the sensors calculate the exact place of touch and the system executes the command.
The surface acoustic wave system is considered the most efficient of all, as it allows 100% of the light produced to pass through, which makes the image perfectly clear.
The screens that use the microcamera technology were developed by Microsoft and registered under the name of Surface. These screens have some cameras on the edges of the screen that capture the touch and send the coordinates of the location to the processor, which converts them into a command.
The main advantage of technology touch screen is space saving as it eliminates keyboards and mice, in addition to allowing greater interactivity between man and computer. The trend is for touchscreens to continue to evolve and spread with other technologies, such as voice and facial expression recognition, further enhancing real-world interaction with the virtual.
By Mariane Mendes
Graduated in Physics
