Touch Screens: A Pressing Technology

1118 B9
Apple
Apple Corporation is a pioneer in the field of consumer
electronics. With their innovative designs, Apple products
have been setting new standards to which other technology
is compared. In 2007, Apple revealed the iPhone, changing
the face of telecommunications and touch screen technology
[10]. This device was revolutionary because it incorporated a
cell phone, iPod, and Internet communications device,
making it the only electronic device you need [11]. Apple
also created a version of this device to be the next generation
of iPod, called the iPod Touch or the iTouch. It is very
similar to the iPhone, except for the difference that it does
not have cell phone capabilities. For our purposes, these
devices will be described as interchangeable, because they
both rely on the same touch technology and the same userinterface
[9].
manipulate documents, images, and other files with motions
that feel like the task actually being completed, the user is
able to work more efficiently and with less specific training
or knowledge.
Apple recently announced their next step in the field of
touch screen technology: the iPad. Little is known about this
device, aside from general technical descriptions of what it
can do, and its 9.7-inch multi-touch display [9]. It can be
assumed that it operates very similarly to that of the iPhone
and iPod touch. This device was designed to browse the
web, read and send email, view photos, movies, listen to
music, play games, and read e-books, among many other
things [13]. With these tasks in mind, the iPad is creating a
new market for touch screen devices, much as the iPhone
changed the mobile phone industry. By integrating
innovative hardware, and creating arguably the most
intuitive user interface available, Apple continues to raise
the bar for all of their competitors in the consumer touch
screen industry.
PROS AND CONS
FIGURE 5
APPLE IPHONE [9]
The iPhone and iTouch both use a projected capacitive
touch screen, and are often used as examples in comparing
projected capacitive technology to other touch screen
technologies [10]. The patent application for this system is
where most of our knowledge of the screen is from. It
describes two different types of touch technology, selfcapacitance
and mutual capacitance [12]. Self-capacitance is
“a simple passive array of 2436 sensing electrodes in a
single plane” [12]. Mutual capacitance, on the other hand,
works much more like other capacitive touch screens. By
setting two layers on top of each other, aligning the
measuring strips perpendicular to each other, and calculating
the touch point based on the X and Y coordinate of the
touch, greater accuracy is achieved [10]. Another
technologically relevant aspect of the iPhone is its use of
multi-touch input, which allows for 15 touches at a time
[12]. It is with this technology that the iPhone and iPod
touch revolutionized the touch screen industry.
These devices are important to the development of
touch screen technology, because of their superior user
interface (UI). There are six main functions of the iPhone’s
touch screen: “Single tap to select or activate something,
double tap to change the display format, drag and drop to
move something, a stroke (“swipe” or “flick”)
up/down/left/right to scroll, “pinching” two fingers together
to shrink something,” and “spreading” two fingers apart to
enlarge something” [10]. These intuitive controls have set a
new precedent for all user interfaces. By being able to
The two types of infrared systems are internal reflection and
infrared grid. Infrared grids systems are reliable and can be
manufactured inexpensively into appropriate sizes. Due to
the grid of lasers and sensors, users do not need to press
fully down on the screen putting less wear on screen
increasing the life expectancy of the unit. The grid also
increases the precision of the users touch.
Internal reflection systems are large systems because
of the space required for cameras to accurately measure the
shadow produced by the infrared LEDs. The large space
required for larger instruments does make internal reflection
devices the most accurate touch screen technology. Units
like the Microsoft Surface, the leading internal reflection
device, are also able to increase their multi-touch capabilities
to 300 plus touches.
Resistive touch screen technology is the cheapest of
the different types of touch screens; however, there are a few
drawbacks. The first problem with this technology is the
flexibility of the top layer of screen. This causes the ITO
coating to crack due to the continual stretching and
retracting of the flexible later [3]. This wear also relates to
the air gap between the ITO layers. This gap allows dirt and
dust to collect between the two conductive surfaces, making
the display appear dirty. Additionally, these devices are “less
than ideal for harsh environments,” due to the fact that they
are vulnerable to temperature and humidity changes, which
would affect the accuracy of the touch screen [3]. This is not
to say that they do not perform consistently under standard
conditions. One benefit of this technology is that the user is
able to use his or her finger or a stylus as input devices [3].
Overall, resistive touch screens perform very well,
considering that they are the cheapest of the different touch
screens.
University of Pittsburgh April 10, 2010
TENTH ANNUAL FRESHMAN CONFERENCE
4