Touch screen

Touch Screen

Touch Screen: interactive device that uses a liquid crystal display 
and touch-sensitive sensors. User is able to switch between 
applications, rotate an image, zooming in on document or draw a 
picture. 
Advantage:
-simple
-save space
Disadvantage:
-sometimes screen is not sensitive 
-if screen is damaged, touch screen sometimes won't work

It uses 3 systems:  
-resistive = has a glass panel covered with a metallic layer. 
The layers contact the electric current. The change in the electric 
field can state where the user touched the screen. 
It isn't that expensive and you can use gloves. However, the 
visibility is poor in sunlight and vulnerable to scratches. 
-capacitive = layer that is used to store electrical charge on glass 
panel. 
It is medium cost and screen visibility is good in strong sunlight. 
Also, the screen is durable. However, it only allows the use of 
bare fingers. 
-infra red (heat and optical) 
=Heat-sensitive uses glass as the screen material and needs a warm 
object to carry out an operation
=Optical uses glass as the screen material and uses an array of 
sensors.
It allows multi-touch technology, the optical one can be used with 
gloves, and has a good durability. However, it is very expensive and 
and heat-sensitive only allows finger for input.