The coordinates for a touch event are processed is essentially the same way as a mouse click. If the user touch his IPad screen at the location of a button leveled Calendar, the area his touch generates coordinates and sends them to processors.
The processor compares the coordinates to the image displayed on the screen to find out what is the coordinate and then responds, in this case opening user appointment calendar.
Three types of touch screens most in use today are capacitive, resistive, and surface wave touch screens.
Capacitive touch screens
A capacitive touch screens has a layer of material that stores electrical charges coating the surface. When a finger touches the screen, it conducts a small amount of the electrical charge reducing the charge on the capacitive layer. This causes oscillator circuit located at corner of the screen to vary in frequency depending on where the screen was touched.
Resistive touch screen
The second type of touch screen is a resistive touch screen. A metallic conductive and resistive layer held apart by spacers cover a resistive touch screen. The thin layers are separated by invisible separator dots.
When a user touches a resistive touch screen, the conductive and resistive layers connect in the location of the touch. This detected by the touch-screen controller, which interprets it as a vertical/horizontal coordinate on the screen and registers the appropriate touch event.
Surface wave technology
Surface wave technology passes ultrasonic waves over the touch screen. Touching the screen absorbs portions of the waves, which then allows the touch screen controlled to calculate the position at which the object touched the screen.
Touch screen technology has really changed the way people interact with electronic devices. Most people find it easier to point at an icon on a screen than to use a keyboard and mouse.
Touch screen technology
