Resistive Touch is another category of digitizer screen technology. This type of technology works by simple “pressing” on screens to activate the desired result. When a user makes contact with the surface of the touchscreen, the two sheets are pressed together. A horizontal and vertical grid is overlaid upon two sheets, such that when a users actions push these sheets together, the computer registers the precise location of the touch. Because this type of touchscreen can sense input from contact with nearly ANY object (finger, stylus, pen, pointer) resistive touch screens are known as a “passive” (non electric) technology. This means that you can use a finger, stylus, or almost any type of device to active the screen. It is not the most common choice for consumer devices like the iPad or iPhone.
Resistive touchscreens are touch-sensitive displays generally created using two flexible layers coated with a resistive material then separated by micro-dots or an air gap. These displays can be composed of different types of metallic layers. One type is called Matrix, in which striped electrodes on substrates such as glass or plastic face each other. The second type is called Analogue which consists of transparent electrodes without any patterning facing each other. It is currently knows that analogue offers lowered production costs.
For example, during operation of a four-wire touchscreen, a uniform, unidirectional voltage gradient is applied to the first sheet. When the two sheets are pressed together, the second sheet measures the voltage as distance along the first sheet, providing the X coordinate. When this contact coordinate has been acquired, the voltage gradient is applied to the second sheet to ascertain the Y coordinate. These operations occur instantly registering the exact touch location as contact is made, provided the screen has been properly calibrated for variations in resistivity.
Resistive touch screens enable high resolution providing accurate touch control. Because the touchscreen responds to pressure on its surface, contact can be made with a finger or any other pointing device. For this reason, it is not the technology used in smartphones or tablets such as iPhones, iPads, Kindle devices or other devices that use a human finger as the most common technology for interface.