A capacitive touch screen is constructed out of glass with a coating of capacitive material
electrodeposited over its surface. Oscillator circuits at the corners of the capacitive glass measure
the capacitance of a person touching the glass surface. Each oscillator will vary in frequency
according to where a person touches the surface. The touch screen controller measures the
frequency changes to determine the X and Y coordinates of the touch. The drawback is that
capacitive touch screen cannot be activated by any non-conductive material, including a gloved
These are three main types:
Surface Capacitive – An exposed ITO conductor on the surface that is touched directly.
Commonly seen in newer household appliances.
Projected Capacitive – Contains two layers of conductors, typically glass. Projected capacitive
has higher accuracy due to the separate scanning of the top and bottom layers. This is the most
common technology used in combination with small format LCD displays.
Single-layer Capacitive – Contains only one layer, with the ITO conductive film underneath
this layer, which is typically glass. Single-layer capacitive has a lower accuracy as the single
conductive layer both emits and receives the signal.