A touch screen or simply touch screen is an assembly of an input and output unit. Usually the touch screen is typically layered over an internal non-volatile memory of an electronic information processing device. While the system might be a smartphone, tablet, laptop or desktop computer the screen is most often an LCD or LED display. The input to the device can come in the form of a stylus, finger, foot, voice, or any other form of input.
How does the touch screen work? The screen is composed of many tiny semi-transparent or transparent dots or perhaps polygonal ones. These dots are electrically charged so when a user touches one of them it charges up the finger. In a way this charge is like an electrical charge running through a person’s finger. Then when that finger goes near the screen, it reacts by creating a small electric impulse which is interpreted by the circuitry.
Touch screen displays for laptops have been around for quite some time now. This is because laptops are used by people in a wide variety of settings and because they do not have much to protect from. They can get very hot from other items placed on the desk or even accidentally hits against them. Touch screens can also get easily scratched so they need to be kept away from rough surfaces. Touch screens for laptops are therefore more susceptible to damage than a typical computer or smartphone would be.
What makes capacitive touch screens work is that a very small amount of current is run through the finger when it is touched. When the finger stays still, the electrical charge runs through the finger, which in turn causes the pixel to create a very small image. This is different from the resistive type which has a large change in resistance. The resistive type can get much hotter causing the pixels to turn off and on constantly, causing the ghosting effect mentioned earlier.
The modern touch screen panels are made up of several thin layers of semiconductors including metallic layers as well as non-metallic ones like the liquid crystal display or LCD touch screen layer. Inside the layers there are electrical signals which are either transmitted through a small gap between the two layers or through the surface wave. The electrical signal is then processed by a processor just like any other computer input device.
The main disadvantage of capacitive touch screens is that they are slow to respond and can often respond by moving to other areas of the screen. This is because the resistive layer has to transfer the energy to the touch event itself, which slows the process down. The new capacitive touch screens on the market today are based on an advanced type of scanning technology, which can quickly identify where the finger is located so that it can then simply push the finger away from the area where it originated. The result is much faster and more responsive. Although slower initially, this type of screen protector reduces finger damage. Also, since the screen itself is not part of the sensitive circuitry, it is less susceptible to scuff marks and bumps than resistive touch screens.
One of the more common drawbacks of capacitive touch screen technology is that many objects, especially metal surfaces will cause the pixels to be activated even when they are not touching active. This is called screen washing. When an object is touched, the individual finger can transfer pressure to the screen, activating the pixels. Screen washing can be very damaging to these type of input devices. Shielding against screen washing can help to minimize the damage to the sensitive electronics.
Touch screens can make a computer mouse or stylus easier to use, but they can also limit the motion of the user’s fingers. The user’s fingertips need to rest directly on the surface of the input device in order to make contact. If the finger has not been lifted off the computer mouse or stylus, then the user can still use the device. If the finger is lifted off the device, the user can no longer point, gesture or rotate the fingers on the touch screen. This makes using a stylus or other input device difficult, if not impossible, if the finger is lifted off the input device.