Editing Touchscreen (section)

==== Mutual capacitance ====
An electrical signal, imposed on one electrical conductor, can be capacitively "sensed" by another electrical conductor that is in very close proximity, but electrically isolated—a feature that is exploited in mutual capacitance touchscreens. In a mutual capacitive sensor array, the "mutual" crossing of one electrical conductor with another electrical conductor, but with no direct electrical contact, forms a [[capacitor]] (see [[touchscreen#Construction]]).

High frequency voltage pulses are applied to these conductors, one at a time. These pulses capacitively couple to every conductor that intersects it.

Bringing a finger or conductive stylus close to the surface of the sensor changes the local electrostatic field, which in turn reduces the capacitance between these intersecting conductors. Any significant change in the strength of the signal sensed is used to determine if a finger is present or not at an intersection.<ref>{{cite web|url=https://onlinedocs.microchip.com/pr/GUID-A8A0085D-58D1-4E41-A07D-B93BFDE11AFE-en-US-4/index.html?GUID-F186B556-F266-4585-830D-1CCE04045D0E|title=Mutual Capacitance|access-date=2023-04-26}}</ref>

The capacitance change at every intersection on the grid can be measured to accurately determine one or more touch locations.
 
Mutual capacitance allows multi-touch operation where multiple fingers, palms or styli can be accurately tracked at the same time.The greater the number of intersections, the better the touch resolution and the more independent fingers that can be detected.<ref>{{cite web|url=https://walkermobile.com/Touch_Technologies_Tutorial_Latest_Version.pdf|title=Touch technologies|access-date=2023-04-26}}</ref>
<ref>{{cite web|url=https://fieldscale.com/learn-capacitive-sensing/self-mutual-capacitive-touch-sensors/|title=Self vs Mutual Capacitance|work=Fieldscale |access-date=2023-04-26}}</ref> This indicates a distinct advantage of diagonal wiring over standard x/y wiring, since diagonal wiring creates nearly twice the number of intersections.

A 30 i/o, 16×14 x/y array, for example, would have 224 of these intersections / capacitors, and a 30 i/o diagonal lattice array could have 435 intersections.

Each trace of an x/y mutual capacitance array only has one function, it is either an input or an output. The horizontal traces may be transmitters while the vertical traces are sensors, or vice versa.