Editing Touchscreen (section)

==Construction==
There are several principal ways to build a touchscreen. The key goals are to recognize one or more fingers touching a display, to interpret the command that this represents, and to communicate the command to the appropriate application.

'''<big>Multi-touch capacitance screens</big>'''

A very simple, low cost way to make a multi-touch capacitance touchscreen, is to sandwich an x/y or diagonal matrix of fine, insulation coated copper or tungsten wires between two layers of clear polyester film. This creates an array of proximity sensing micro-[[capacitors]]. One of these micro-capacitors every 10 to 15&nbsp;mm is probably sufficient spacing if fingers are relatively widely spaced apart, but very high discrimination multi-touch may need a micro-capacitor every 5 or 6&nbsp;mm. A similar system can be used for ultra-high resolution sensing, such as fingerprint sensing. [[Fingerprint sensor]]s require a micro-capacitor spacing of about 44 to 50 microns.<ref>{{cite journal|title=Transparent fingerprint sensor|journal=Sensors |date=January 2018 |volume=18 |issue=1 |page=293 |doi=10.3390/s18010293 |doi-access=free |last1=Seo |first1=Wonkuk |last2=Pi |first2=Jae-Eun |last3=Cho |first3=Sung Haeung |last4=Kang |first4=Seung-Youl |last5=Ahn |first5=Seong-Deok |last6=Hwang |first6=Chi-Sun |last7=Jeon |first7=Ho-Sik |last8=Kim |first8=Jong-Uk |last9=Lee |first9=Myunghee |pmid=29351218 |pmc=5796292 }}</ref>

'''<big>Single touch resistive touchscreens</big>'''

In the resistive approach, which used to be the most popular technique, there are typically four layers:

* Top polyester-coated layer with a transparent metallic-conductive coating on the bottom.
* Adhesive spacer
* Glass layer coated with a transparent metallic-conductive coating on the top
* Adhesive layer on the backside of the glass for mounting.

When a user touches the surface, the system records the change in the electric current that flows through the display.

'''<big>Dispersive signal</big>'''

Dispersive signal technology measures the [[piezoelectric effect]]—the voltage generated when mechanical force is applied to a material that occurs chemically when a strengthened glass substrate is touched.

'''<big>Infrared</big>'''

There are two infrared-based approaches. In one, an array of sensors detects a finger touching or almost touching the display, thereby interrupting infrared light beams projected over the screen. In the other, bottom-mounted [[thermographic camera|infrared cameras]] record heat from screen touches.

In each case, the system determines the intended command based on the controls showing on the screen at the time and the location of the touch.