Touch Screen Backstory
Automobiles, airplanes, computers, and steam engines—touchscreens belong in the cliche
of these famous innovations because they do not have a particular inventor and
a real, "Eureka" moment : in other words, no one man or woman invented
the touchscreen.
The first innovation
that comes close in resemblance to using a touchscreen was known as a light
pen, a stylus with a photocell in one
place end, and a cable connecting the computer to the other end, that is able
to draw graphics on the screen. It was developed in the 1950s and
forms an integral part of one of the foremost computer systems to possess
graphics, Project Whirlwind. Light pens do not work like recent
touchscreens. Eventhough, there was nothing spectacular about the screen
itself,all the work took place within the pen and the computer it was connected
to.
In
the 1960s and early 1970s, a different approach in the development of
touchscreens emanated from the research of computer scientists who were
specialists in a field known as human-computer interaction (HCI), which sought to bridge the gap between people
and computers. Among them were Douglas Engelbart, the inventor of the computer mouse; Ivan
Sutherland, a foremost authority in computer
graphics and virtual reality; and
Alan Kay, a colleague of Sutherland's who assisted greatly in pioneering the graphical user interface (or GUI—the picture-based desktop used on nearly all
modern computers).
The
first device that worked in a way similar to a modern touchscreen was known as
a Discriminating Contact Sensor, and was patented on October 7, 1975 by George S.
Hurst and William C. Colwell of Elographics, Inc. Just like a modern resistive
touchscreen, it was a device having two electrically conducting contact layers
spaced by an insulating layer that can be pressed together using a pen. It was
designed to be used with a writing device and not by the writer's
hand". So it does no resemble a modern, finger-operated touchscreen.
A lot of people
thought touchscreens surfaced when Steve Jobs launched Apple's
iPhone,way back in 2007—but touch-operated, handheld computers had been in
use for about 20 years earlier. One of the foremost was the Linus Write-Top,
a large tablet computer unveiled in 1987. Five years later, Apple unveiled the
predecessor of its iPhone in the shape of Newton, a handheld computer produced
by the Japanese Sharp Corporation. Operated by a pen-like stylus, it featured
pioneering but somewhat erratic handwriting recognition but was a commercial
failure. Touchscreen input and handwriting recognition also featured in the
Palm series of PDAs (personal digital assistants), which was
widely used in the mid-1990s. All modern touchscreen devices owe credit to
these foremost inventors and their inventions.
Touchscreens
In
the years of the computer,the means to make a computer perform a task,was to
input it a pile of cards with holes perforated in them. Luckily, things have improved further from then on. Now we make our computers perform tasks,just by
pointing and clicking with a mouse or by shouting out commands using voice recognition software. A revolution yet to come will allow computers more easier to use with touch-sensitive screens. Mobile phones such as Apple's
iPhone, ebook readers, and certain MP3 players already using some touch control and pcs can to work like that too.
Keyboards and switches
A
touchscreen is likened to an invisible keyboard joined to the front of your
computer monitor. To know how it works, it will assist ,if you know how a keyboard works. Normally, all keys on a keyboard,behaves like an electrical switch. When a
key is pressed down,an electric circuit is completed and current flows. The amount of current depends on the key you press and that's how your computer knows what you're typing.
Within a keyboard,there are two distinct layers of
electrically conducting plastic separated
by an insulating plastic membrane with holes perforated in it. In reality, there's one hole beneath every key. When you push a key, you push the upper conducting layer
down towards the lower layer ,so the two layers meet and touch through the
hole. Current flows between these layers and the computer detects that you've pressed
a key. Tiny spring like pieces of rubber,placed beneath
every key,allows them return back to their original position, breaking the circuit
when released.
Touchscreens must accomplish something close to this on the surface of your computer screen. Technically they can not employ switches, membranes, and bits of plastic or they would cover the view of the screen beneath. So a more ingenious method for
sensing your touch is used(completely invisibly).
How touchscreens work
Various types of touchscreen operate in numerous ways. Some are able to detect one finger at
a time and get extremely confused if you try to press in two places at once.
Others can easily detect and differentiate between more than one key pressed at once. These
are some of the known and common types:
Resistive
Resistive touchscreens
(presently the most common) work just like "transparent
keyboards" laid on top of the screen,having an flexible upper layer
of conducting polyester plastic fixed to a hard lower layer of conducting glass and
separated by an insulating membrane. When you press on the screen, the polyester touches the glass and complete a circuit,like pressing a key on a keyboard. A chip within the screen figures out the coordinates and position of the
place you touched.
Capacitive
These screens are assembled using multiple layers of glass. The innermost layer conducts electricity and so does
the outer layer,efficiently,that the screen behaves like two electrical
conductors separated by an insulator,just like a capacitor.
When you bring your finger close to the screen, you alter the electrical field by
a particulr amount that varies according to where your hand is placed. Capacitive
screens can be touched in multiple places at once. Unlike other type of touchscreen, they don't function, if you touch them with a plastic stylus
(the plastic is an insulator and prevents your hand from affecting the
electric field).
Infrared
Like the eye beams of an intruder alarm, an infrared touchscreen employs a grid networks of LEDs and light-detector photocells placed at opposite points on the screen. The LEDs beam infrared light in front of the screen—a bit like an
invisible spider's web. If you touch the screen at a certain point, you
interrupt two or more beams. A microchip inside the screen can calculate where
you touched by seeing which beams you interrupted. The touchscreen on Sony
Reader ebooks (like the one pictured in our top
photo) works this way. Since you're interrupting a beam, infrared screens work
just as well whether you use your finger or a stylus.
Surface Acoustic Wave
Surprisingly, this
touchscreen technology detects your fingers using sound instead
of light. Ultrasonic sound waves (too high pitched
for humans to hear) are generated at the edges of the screen and reflected back
and forth across its surface. When you touch the screen, you interrupt the
sound beams and absorb some of their energy. The screen's microchip controller
figures out from this where exactly you touched the screen.
Near field imaging
Have
you noticed how an old-style radio can buzz and whistle if
you move your hand toward it? That's because your body affects the
electromagnetic field that incoming radio waves create in and around the antenna. The closer you get, the
more effect you have. Near field imaging (NFI) touchscreens work a similar way.
As you move your finger up close, you change the electric field on the glass
screen, which instantly registers your touch. Much more robust than some of the
other technologies, NFI screens are suitable for rough-and-tough environments
(like military use). Unlike most of the other technologies, they can also
detect touches from pens, styluses, or hands wearing gloves.
Light pens
Light pens were an
early form of touchscreen technology, but they worked in a completely different
way to modern touchscreens. In old-style computer screens, the picture was
drawn by an electronbeam that scanned back and forth,
just like in a cathode-ray tube television.
The pen contained a photoelectric cell that detected the
electron beam as it passed by, sending a signal to the computer down a cable.
Since the computer knew exactly where the electron beam was at any moment, it
could figure out where the pen was pointing. Light pens could be used either to
select menu items or text from the screen (similar to a mouse) or, as shown in
the picture here, to draw computer graphics.
Advantages of touchscreens
The
great thing about touchscreen technology is that it's incredibly easy for
people to use. Touchscreens can display just as much information (and just as
many touch buttons) as people need to complete a particular task and no more,
leading people through quite a complex process in a very simple, systematic
way. That's why touchscreen technology has proved perfect for public
information kiosks, ticket machines at railroad stations, electronic voting
machines, self-service grocery checkouts, military computers, and many similar
applications where computers with screens and keyboards would be too
troublesome to use.
Some of us are lucky
enough to own the latest touch phones, which have multi-touch screens. The big
advantage here is that the display can show you a screen geared to exactly what
you're trying to do with it. If you want to make a phone call, it can display
the ordinary digits 0–9 so you can dial. If you want to send an SMS text
message, it can display a keyboard (in alphabetical order or typewriter-style QWERTY order, if you prefer).
If you want to play games, the display can change yet again. Touchscreen
displays like this are incredibly versatile: minute by minute, they change to
meet your expectations.
All of us with
smartphones (modern cellphones), ebook readers, and tablet computers are now
very familiar with touchscreen technology. Back in 2008, Microsoft announced that touch
technologies would feature prominently in future versions of the Windows
operating system—potentially making computer mice and keyboards obsolete—but
almost a decade later, most of us are still locked into our old-style computers
and operating systems, and the old ways of using them. Though it could be a while
before we're all prodding and poking our desktop computers into action,
touchscreen technology is definitely something we'll be seeing more of in
future!
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