INTRODUCTION
In our modern world, we are
using many technological tools. In this tool display is the tool we use most
frequently. The display is part of our life. We can not imagine a single day
without display. The display has 2 kinds one is a touchscreen display and another
one is a non-touchscreen display. We can see a non-touchscreen display in our
old generation Television and a touchscreen display on a smartphone and some
smart TVs. In touchscreen display, many touch sensors are used to play an
active role in touchscreen technology.
Resistive touch screens were once the
most dominant type of touch screen interfaces incorporated on a LCD Display,
but their use has definitely declined. In the current market place the best fit
for resistive touch screens are in low-cost Liquid Crystal Display designs or
where the user must wear gloves. These markets include medical, industrial and
military environments. In more recent years capacitive touch screen have gained
in market share and in user popularity. The extremely popular smartphones and
tablets in recent years incorporate capacitive touch functionality.
There
are 3 types of touchscreen we use nowadays. One is a resistive touchscreen and
the second one is an infrared touchscreen and the third one is a capacitive
touchscreen display. So, first of all, I am going to tell you about the
resistive touchscreen display. Is has two types of layer one are resistive and
another one is conductive. In this display where we touch that is made of
polyester and the lower part of that display is made of glass. Both of this
part is separated by a spacer in between. A small amount of current is flowing
through this two-layer. When we touch that screen the upper layer touches the
bottom layer and a small amount of current in that section is changed and this
change is recognized by a processor and then the coordinate is found by the
processor. This is how the resistive display works. But it has some problems
too. It does not support the multitouch functionality and we cannot zoom any
picture and the screen visibility rate is very poor due to the high reflection
of ambient light from the two-layer system and it is quite harder to know
what’s is written there in a sunny day. For this problem, our method is the
exact solution. Our system capacitive touchscreen display has multitouch
functionality and the screen is very clear to visible.
There are two different types of metallic layers.
The first type is called matrix, in which striped electrodes on
substrates such as glass or plastic face each other. The second type is called analogue
which consists of transparent electrodes
without any patterning facing each other. As of 2011 analogue offered lowered
production costs. When contact is made to the surface of the touchscreen, the
two sheets are pressed together. On these two sheets there are horizontal and
vertical lines that, when pushed together, register the precise location of the
touch. Because the touchscreen senses input from contact with nearly any object
(finger, stylus/pen, palm) resistive touchscreens are a type of
"passive" technology.
For example, during operation of a four-wire
touchscreen, a uniform, unidirectional voltage
gradient
is applied to the first sheet. When the two sheets are pressed together, the
second sheet measures the voltage as distance along the first sheet, providing
the X coordinate. When this contact coordinate has been acquired, the voltage
gradient is applied to the second sheet to ascertain the Y coordinate. These
operations occur within a few milliseconds, registering the exact touch
location as contact is made, provided the screen has been properly calibrated
for variations in resistivity.
Resistive touchscreens typically have high
resolution (4096 x 4096 DPI or higher), providing accurate touch
control. Because the touchscreen responds to pressure on its surface, contact
can be made with a finger or any other pointing device.
One of the earliest electronic
displays is the cathode ray tube (CRT), which was first demonstrated in 1897
and made commercial in 1922. The CRT consists of an electron gun that forms
images by firing electrons onto a phosphor-coated screen. The earliest CRTs
were monochrome and were used primarily in oscilloscopes and black and white
televisions. The first commercial color CRT was produced in 1954. CRTs were the
single most popular display technology used in television sets and computer
monitors for over half a century; it was not until the 2000s that LCDs began to
gradually replace them. A derivative of CRTs was storages tubes, which could
retain information displayed on them, unlike standard CRTs which need to be
refreshed periodically. In 1968, Tektronix introduced the direct view bistable
storage tube, which went on to be widely used in oscilloscopes and computer
terminals. Between 1948-1950 the first color CRT-TV was invented by RCA
laboratories. On December 17, 1953, CRT-TV began its commercial broadcasting.
In 1957 the flip-flap/disk
display in invented. In 1964 monochrome plasma display was invented. In 1968
LED display was invented. In 1968 egg-crate display was invented. In 1967
Vaccum fluorescent display was invented. In 1971 twisted nematic field effect
LCD was invented. In 1888, liquid crystals were first discovered in cholesterol
extracted from carrots by Austrian botanist and chemist, Friedrich Reinitzer.In
1962, RCA researcher Richard Williams generated stripe patterns in a thin layer
of liquid crystal material by the application of a voltage. This effect is
based on an electrohydrodynamic instability forming what is now called
“Williams domains†inside the liquid crystal. James Fergason holds some patents
in LCD with US patent number is 3,731,986.
The touchscreen technology
first invented in between 1965 to the 1967 year. E.A. Johnson is the first
touchscreen technology inventor of the world who lived in Malvern, UK. In 1968
E.A. Johnson published an article named touchscreen system for air traffic
control. There he described what he invented most clearly.
In 1971, a "touch
sensor" was developed by Doctor Sam Hurst (founder of Elographics) while
he was an instructor at the University of Kentucky. This sensor called the
"Elograph" was patented by The University of Kentucky Research
Foundation. The "Elograph" was not transparent like modern touch
screens, however, it was a significant milestone in touch screen technology.
The Elograph was selected by Industrial Research as one of the 100 Most Significant
New Technical Products of the Year 1973. In 1974, the first true touch screen
incorporating a transparent surface came on the scene developed by Sam Hurst
and Elographics. In 1977, Elographics developed and patented a resistive touch
screen technology, the most popular touch screen technology in use today. In
1977, Siemens Corporation financed an effort by Elographics to produce the
first curved glass touch sensor interface, which became the first device to
have the name "touch screen" attached to it. On February 24, 1994,
the company officially changed its name from Elographics to Elo TouchSystems.
Elographics patents
In 1983, the computer
manufacturing company, Hewlett-Packard introduced the HP-150, a home computer
with touch screen technology. The HP-150 had a built-in grid of infrared beams
across the front of the monitor which detected finger movements. However, the
infrared sensors would collect dust and require frequent cleanings.
The nineties introduced
smartphones and handhelds with touch screen technology. In 1993, Apple released
the Newton PDA, equipped with handwriting recognition; and IBM released the
first smartphone called Simon, which featured a calendar, notepad, and fax
function, and a touch screen interface that allowed users to dial phone
numbers. In 1996, Palm entered the PDA market and advanced touch screen
technology with its Pilot series.
In
2002, Microsoft introduced the Windows XP Tablet edition and started its entry
into touch technology. However, you could say that the increase in the
popularity of touch screen smartphones defined the 2000s. In 2007, Apple
introduced the king of smartphones, the iPhone, with nothing but touch screen
technology.
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