A touch screen or a capacitive touchscreen is an assembly of two physical input and output devices. The touch screen is usually layered over an electronic view of a data processing system. The display is most often the LCD or LED touch screen while the system is generally a smartphone, tablet, or laptop. These systems provide the user with a point of reference that they can use to interact with the external environment as well as with the computing device itself. Touchscreens are used in many devices such as digital signage, medical equipment, desktop computers, video game consoles, trains, and other consumer electronic appliances.
Touchscreens were first developed for the purpose of inputting and displaying computer input devices such as keyboards and pointing devices. Touchscreens are generally smaller than a typical laptop keyboard and are available in a variety of sizes including 17″ models. With the advent of touch screens, portable devices such as smart phones, tablets, and laptops have become common place accessories for consumers. The convenience provided by touch screens has prompted manufacturers to develop even smaller touch screen technology for use in smaller devices. As a result, there are now touch screen displays available for use in portable devices such as pens, fingers, and even stylus pens.
The touch screen utilizes an electric charge to register and track a finger or any other moving object. The electrical charge is conducted between the finger and the electric display screen. When the finger moves across the screen, an invisible electric field lines up with it. This electric field cancels out the effects of any static electricity that could have been induced by a flat surface. Instead, the computer’s virtual touch point is correctly located based on your finger’s motion. The accuracy of these systems is based on a very complicated algorithm that takes the data from the finger’s position and correlated with the electrical charge that is conducted.
When your finger brushes against the touch screen, some of the electricity produced is transmitted to the sensitive areas of the screen causing the dots to move to the color of the finger. Because the screen is so small, the dots usually move very quickly. The speed of the dots’ movement also depends on the thickness of the skin and the thickness of the finger. Usually a finger is required to make a light contact with the screen. Although a touch screen can be used if the user is standing rather than sitting, fingers are still required to make direct contact with the screen to provide full mobility and accuracy.
The finger technique allows the most amount of movements possible without making any contact with the surface. This is the reason that stylus pens are generally used with touch screens instead of pens. Using a stylus, you can move the pen from side to side and up and down. Many stylus products are also equipped with a sensor that detects the pressure from the fingers and can tell when the pen has been lifted past a specific point.
One major drawback of using a stylus for touch screens is accuracy. Sometimes the stylus results in minor disturbances in the signal, which then cause incorrect readings. This can cause the results to be off a bit, which can be frustrating when trying to input data. Even more frustrating is if you are typing data into a document or spreadsheet and the result is an error message stating that the touch screen was incorrectly detected. In these cases it may be necessary to take the stylus away and replace it with a different one.
Touch screen technology uses two types of technologies to detect finger pressure: capacitive and infrared. Capacitive touch screen uses liquid crystals as the keypad and detects your finger contacts through the vibrations produced by the tapping of your fingers. Infrared beams are emitted from a transmitter at various depths, above and below the surface, to capture the IR waves produced by your finger. The IR beams are then reflected back to the keypad and converted by the detectors into an electrical signal. The amount of power required to run the transmitter and detector will determine the maximum depth to which the transmitter can detect the IR beams. Therefore, touch screens generally have a maximum transmitting distance of thirty inches from the surface, while handheld infrared beams can detect anything up to nine inches away.
Although capacitive touch screens are quite accurate and rely on small amounts of movement to detect their target, they are prone to finger fatigue and finger damage. They also require frequent re-centering to maintain accuracy, which makes them less flexible than other technologies. On the other hand, capacitive touch screens have much longer life spans and have much easier ‘wear and tear’ issues. However, they are not as rugged as their Resistive technologies and are much less resistant to shock. Some assistive technologies, such as some kinds of capacitive technology, have additional capabilities built into them that combine for improved resistance to wear and tear and more extended life.