This article describes how PCAP technology works

Projected Capacitive touch sensing (PCAP) is the technology currently used in all premium tablets and smartphones now readily accessible in most commercial applications as well

How it works:

• Rows and columns of transparent conductors
• Electrical pulses sent through drive electrodes
• Receive electrodes pick up signal through capacitive coupling
• Conductive objects (finger, PCAP stylus) touching the screen alter the capacitive coupling which is detected by the touch controller
• True position of multiple simultaneous touches is output from the controller to the host device (typically through USB or I2C interface)

Self-Capacitance

• Capacitance of a single electrode to ground – CS 
• Each electrode is measured individually. 
• A conductive stylus (finger or other) adds capacitance to ground.
• This change of charge is measured by the controller.

Key Benefits 

• 12+ point true multi-touch 
• Fast and sensitive touch response 
• High accuracy and linearity 
• Excellent optical clarity 
• Long-term durability
• Drift-free operation requires no calibration
• Provides the familiar look, feel, and performance of consumer phones & tablets