Transcript Touch Screen Technology

Touch screens emerged in the second
half of the 1960’s
 Dr. Samuel C. Hurst invented the touch
screen in 1971.
 First gained visibility in 1972; PLATO
project
 Multi-touch technology.
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Top polyester layer coated 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
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Voltage is applied to each corner
 Electrodes are spread uniformly across
the field.
 Touch finger draws current from each
side proportionally
 Controller calculates position of the
finger from the current
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New XM touch screen display featured in 2009
Hyundai Sonata
Canova Dual Touch screen Laptop from V12 Design
Charlie Card dispensers
Iphone 3GS
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Resistive
Surface Acoustic wave
Capacitive Iphone
Surface Capacitance Iphone
Projected Capacitance
Infrared
Strain gauge
Optical imaging
Dispersive signal technology
Acoustic pulse recognition
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Capacitive touch-screens use a layer of capacitive material to
hold an electrical charge; touching the screen changes the
amount of charge at a specific point of contact.
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Its touch-sensitive screen
includes a layer of
capacitive material, just like
many other touch-screens.
However, the Iphone's
capacitors are arranged
according to a coordinate
system.
Its circuitry can sense
changes at each point
along the grid.
This allows the phone to
determine the location and
movement of simultaneous
touches in multiple locations
The Iphone's screen detects touch through
one of two methods:
Mutual capacitance or self capacitance.
In mutual capacitance, the capacitive
circuitry requires two distinct layers of
material.
 One houses driving lines, which carry
current, and the other houses sensing lines,
which detect the current at nodes.
 Self capacitance uses one layer of
individual electrodes connected with
capacitance-sensing circuitry.
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The Iphone's processor
and software are
central to correctly
interpreting input from
the touch-screen. The
capacitive material
sends raw touchlocation data to the
Iphone's processor. The
processor uses software
located in the Iphone's
memory to interpret the
raw data as commands
and gestures.
Silverman, Jacob. "What is the Apple
iPhone?." 10 January
2007. HowStuffWorks.com.
<http://electronics.howstuffworks.com/ip
hone-qotd.htm> 30 November 2009.
 Wilson, Tracy V. "How the iPhone
Works." 20 June
2007. HowStuffWorks.com.
<http://electronics.howstuffworks.com/ip
hone.htm> 30 November 2009.
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