A review of technologies for sensing contact location on the surface of a display

Touchscreen interactive devices have become increasingly important in both consumer and commercial applications. This paper provides a broad overview of all touchscreen technologies in use today, organized into 13 categories with 38 variations. The 13 categories are projected capacitive, analog resistive, surface capacitive, surface acoustic wave, infrared, camera-based optical, liquid crystal display in-cell, bending wave, force sensing, planar scatter detection, vision-based, electromagnetic resonance, and combinations of technologies. The information provided on each touchscreen technology includes a little history, some basic theory of operation, the most common applications, the key advantages and disadvantages, a few current issues or trends, and the author's opinion of the future outlook for the technology. Because of its dominance, this paper begins with projected capacitive; more information is provided on this technology than on any of the other touch technologies that are discussed. This paper covers only technologies that operate by contact with a display screen; this excludes technologies such as 3D gesture recognition, touch on opaque devices such as interactive whiteboards, and proximity sensing. This is not a highly technical paper; it sacrifices depth of information on any one technology for breadth of information on multiple technologies.