Common problems for touch screens
Many of today's electronic devices -- including cell phones, music players and portable game systems -- have a touch screen. When a touch screen fails, it does not respond when you tap it with your finger or a stylus. This can happen due to several reasons.Common issues can cause using a touch screen to be difficult, or can prevent the touch screen from functioning at all.
Touch screens operate by being able to sense what section of the screen is being touched, and they can figure out what actions to take from there. A properly calibrated screen will ensure that if you touch a part of the screen, it will register the pressure in the correct area. Occasionally, a touch screen can lose its calibration and may not judge the user's input correctly, causing incorrect operations, or it can have difficulty sensing the user's touch at all. This may be sporadic and requires the screen to be recalibrated, which can usually be done by the user from a tool on the computer or peripheral.
Listing 1 Steps in the calibration process
1. Call setCalibrationMatrix() with a perfect set of values (see sample.c) to set the touch screen driver to provide raw (non-translated) data. This way you do not need to build special functions to access the data. Instead you simply get coordinates from the same mechanism as your program.
2. Draw the first target at coordinates (XD0,YD0).
3. Collect the data returned by the touch screen driver and save it as (X0,Y0).
4. Draw the second target at coordinates (XD1,YD1).
5. Collect the data returned by the touch screen driver and save it as (X1,Y1).
6. Draw the third target at coordinates (XD2,YD2).
7. Collect the data returned by the touch screen driver and save it as (X2,Y2).
8. Call setCalibrationMatrix() with the reference display data and resulting touch screen data as arguments.
Scratching and Damaging
Touch screens are incredibly prone to damage because of how often they come into contact with skin and different materials. Mishandled and unprotected screens can suffer scratching damage that may affect the accuracy of the screen and may prevent some portions of the screen from being usable at all. Many peripherals with touch screens will come with styluses, but a rough stylus edge, or styluses used with too much force, can also affect the screen's usability. For any phones or other devices that may normally be carried in pockets, the screens can be damaged by other objects such as keys and spare change.
Well, how to deal with this? the best solution, short of screen replacement, is a screen-protector film. It won't just shield from future scratches—it will make some shallow ones invisible.
Dirt and Grease
Touch screens won't just get damaged by frequent contact. It doesn't take long for grease to start making itself visible on the screens. Even a small amount of dirt or grease may affect how accurate the touch screen is. If left uncleaned, the grease and dirt may actually begin to damage the internal components. However, the main problem is the collection of foreign materials on the screen. Many devices with touch screens come with cleaning cloths that are safe to use and won't damage the screen.
Operation and System
Because of the delicate nature of touch screens, they will sometimes be affected no matter how well you take care of them. Errors registering input or within the device itself may make the system unresponsive. With age, the calibration may begin to falter, the response time may slow and become erratic, and in some cases, the screen may register input that has not been given. Recalibration and refreshing the system may help sometimes, but if the hardware itself begins to fail, the device may become useless.
Touch screen devices are valuable, innovative and creative, but they are also sensitive and easily damaged. Proper care is essential for these devices. Consider protective screens and carrying cases for phones, MP3 players and laptop tablets. Keep the screens and your hands clean, and consult your operating manuals for instructions on how to recalibrate your screen if necessary.
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