Touch Screen Technology
What is Touch Screen Technology?
Touchscreen technology is the direct manipulation type gesture based technology. Direct manipulation is
the ability to manipulate digital world inside a screen without the use of command-line-commands. A device
which works on touchscreen technology is coined as Touchscreen. A touchscreen is an electronic visual
display capable of ‘detecting’ and effectively ‘locating’ a touch over its display area. It is sensitive to the
touch of a human finger, hand, pointed finger nail and passive objects like stylus. Users can simply move
things on the screen, scroll them, make them bigger and many more.
Hailing the History..!!
The first ever touchscreen was developed by E.A Johnson at the Royal Radar Establishment, Malvern, UK
in the late 1960s. Evidently, the first touchscreen was a capacitive type; the one widely used in smart
phones nowadays. In 1971, a milestone to touchscreen technology was developed by Doctor Sam Hurst,
an instructor at the University of Kentucky Research Foundation. It was a touch sensor named ‘Allograph’.
Later in 1974, Hurst in association with his company Demographics came up with the first real touchscreen
featuring a transparent surface. In 1977, Demographics developed and patented a resistive touchscreen
technology, one of the most popular touchscreen technologies in use today.
Ever since then, touchscreen displays are widely used in computers, user interactive machines, public
kiosks, point of sale applications, gaming consoles, PDAs, smart phones , tablets, etc.
Types of Touchscreen Technology
Let us now give an engineer’s eye to this revolutionary technology. A touchscreen is a 2 dimensional
sensing device made of 2 sheets of material separated by spacers. There are four main touchscreen
3) Surface Acoustic Wave
1. Resistive Touchscreen Technology
The resistive touchscreen consists of a flexible top layer made of Polyethylene (PET) and a rigid bottom
layer made of glass. Both the layers are coated with a conducting compound called Indium Tin Oxide (ITO)
and then spaced with spacers. While the monitor is operational, an electric current flows between the two
layers. When a touch is made, the flexible screen presses down and touches the bottom layer. A change
in electrical current is hence detected and the coordinates of the point of touch is calculated by the controller
and parsed into readable signals for the operating system to react accordingly.
Some of the popular devices that use Resistive Touchscreen are Nintendo DS, Nokia N97, HTC Touch
Pro2, HTC Tattoo, Sony Ericsson Satie, etc.
These systems transmit only 75% of light from the monitor. The resistive touchscreen is further divided into
4-, 5-, 6-, 7- and 8-wired resistive touchscreen. While the constructive design of all these modules is similar
there is a major distinction in each of its method to determine the coordinates of touch.
The Four-wire Resistive Touchscreen uses both the layers to calculate the axes information of the touch.
Touch measurement in the 4-wire is a 2 step process. The x-coordinate of the touch point is calculated by
creating a voltage gradient on the flexible layer, and the y-coordinate is determined by creating a voltage
gradient along the bottom layer.
Pros and Cons: Consequently, the 4-wire resistive touchscreen is less durable, feebly accurate and can
drift with environmental changes. However these negatives are divulged only with large-sized touchscreen.
These are relatively cheap, easily available and consume low power.
The Eight-wire Resistive Touchscreen is simply a variation of the 4-wire one with the addition of 4 sense
wires, two for each layer. The sensing points aid in reducing the environmental drift to increase the stability
of the system. The 8-wire systems are employed in sizes of 10.4” or larger where the drift can be significant.
The Five-wire Resistive Touchscreen do not uses the coversheet (flexible layer) in determining the touch
coordinate. All the position sensing is employed on the stable glass layer. In this design, one wire goes to
the coversheet and four wires are deployed to the four corners of the bottom sheet. The coversheet only
acts as a voltage measuring probe. The functioning of the touchscreen remains unscathed even with
changes in the uniformity of the conductive coating over the coversheet.
Pros and Cons: Highly durable, accurate and reliable. This technology involves complex electronics and
is expensive. However, it can be used in sizes up to 22”.
The Six and Seven wire resistive touchscreen is also a variant to the 5 and 4 wire technology respectively.
In the 6-wire resistive touchscreen an extra ground layer is added behind the glass plate which is said to
improve system’s performance. While, the seven–wire variant has two sense lines on the bottom plate.
However, these technologies are as prevalent as their counterparts.
2. Capacitive Touchscreen Technology
The Capacitive Touchscreen Technology is the most popular and durable touchscreen technology used all
over the world at most. It consists of a glass panel coated with a capacitive (conductive) material Indium
Tin Oxide (ITO). The capacitive systems transmit almost 90% of light from the monitor. Some of the devices
using capacitive touchscreen are Motorola Doom, Samsung Galaxy Tab, Samsung Galaxy SII, Apple’s
iPad. There are various capacitive technologies available as explained below.
Surface-Capacitive screens, in this technique only one side of the insulator is coated with a conducting
layer. While the monitor is operational, a uniform electrostatic field is formed over the conductive layer.
Whenever, a human finger touches the screen, conduction of electric charges occurs over the uncoated
layer which results in the formation of a dynamic capacitor. The computer or the controller then detects the
position of touch by measuring the change in capacitance at the four corners of the screen.
Pros and Cons: The surface capacitive touchscreen is moderately durable and needs calibration during
manufacture. Since a conductive material is required to operate this screen, passive stylus cannot be used
for surface capacitive touchscreen.
In the Projected-Capacitive Touchscreen Technology, the conductive ITO layer is etched to form a grid of
multiple horizontal and vertical electrodes. It involves sensing along both the X and Y axis using clearly
etched ITO pattern.
The projective screen contains a sensor at every intersection of the row and column, thereby increasing
the accuracy of the system. There are two types of projected capacitive touchscreen: Mutual Capacitance
and Self Capacitance
3. Surface Acoustic Wave Touchscreen technology
The Surface Acoustic Wave Touchscreen technology contains two transducers (transmitting and receiving)
placed along the X-axis and Y-axis of the monitor’s glass plate along with some reflectors. The waves
propagate across the glass and are reflected back to the sensors. When the screen is touched, the waves
are absorbed and a touch is detected at that point. These reflectors reflect all electrical signals sent from
one transducer to another. This technology provides excellent throughput and image clarity.
Pros and Cons: 100% clarity is obtained as no metallic layers are present on the screen, it can be operated
using passive devices like stylus, glove or finger nail. Screen can get contaminated with much exposure to
dirt, oil which may haunt its smooth functioning.
4. Infrared Touchscreen Technology
In the Infrared Touchscreen Technology, an array of X- and Y- axes are fitted with pairs of IR led s and
photo detectors. The photo detectors detect any change in the pattern of light emitted by the Led s whenever
the user touches the monitor/screen.
The starred assets..!!
The potential novice touchscreen technology has many advantages over the conventional QWERTY
keyboard and monitor. It is very flexible as opposed to its physical counterparts since the digital displays
can be configured anytime at will of the user as per the functionalities. Touchscreen allows users to
customize the interface for example alteration of language and size. By adjusting the size of the keyboard,
user can utilize the spare area for display and other uses. With the decreasing sizeof computers and tablets
these days, touchscreen is an added advantage. Multiple functions has to be performed on a small screen,
touchscreen allows switching to a function at user’s will. For example, virtual keyboard which is an
application of touchscreen is displayed on the screen only when the user allows it to be.
However, there is also the other side of the coin where there some functionality which cannot be performed
using a regular touchscreen like cut-and-paste, right click menu options, drop-down menus.
The Plural Touch Technology..!!
The plural touch technology or the Multi touch is a variant of the touchscreen technology which can detect
two or more touches over its display area at the same time. Some of the common functionalities that require
multitouch interface are zooming in, zooming out, rotating objects, panning through a document, virtual
keyboard, etc. Multi touch Applications technology are found in smart phones like iPhone, Samsung
Galaxy, Nokia N8, Nexus S, Microsoft Touchable, Apple’s iPad and many more.
Apple iPhone: ‘Multitouch’ now is a trademark by Apple who rightly proved it with a bang with the first most
successful multitouch device ever; the iPhone. The first iPhone was unveiled on January 9, 2007. IPhone
is no less than a revolution in the touchscreen industry with its maestro functionalities and applications. It
uses Mutual Capacitance Technology as its touchscreen. The capacitive touchscreen can only be operated
by bare finger or multiple fingers for multi touch.
Microsoft Surface: is a multi touch product from Microsoft that allows multiple users to manipulate digital
content through surface computing. The main feature of this product is its Surface’s interface: Direct
interaction, multi-touch contact, object recognition and multi-user experience. It is not based on and limited
by the conventional touch technology. The surface utilizes Frustrated Total Internal Reflection and
underneath projectors for its display operation. It is indeed a milestone in the multi-touch scenario.
Benefits of Touch Screen Technology
When deciding on new interface technology, whether it is for professional or personal use, the touch screen
component has become a popular option to consider. With a hard durable surface, with a thin plastic screen
shield, touch-screen devices are less prone to screen damage than devices with keypads. Moreover, the
resilient and easy-to-use nature of touch-screen devices make them suitable for users of all ages and skill
Replacing the Mouse and keyboard
The process of using a touch screen monitor allows for the absence of the traditional computer mouse and
keyboard. Without them, the touch screen functions and programs are directly accessible by touching areas
of the screen. The absence of a mouse and keyboard also allows for easier transport and relocation of the
Reality Based Interaction
Having a more direct and natural interaction with electronic devices is an appeal of this technology. Lacking
the multiple devices needed to communicate with traditional computers, touch screen technology creates
a simpler and more intuitive interaction.
Space and Mobility
Standard computer systems that require a mouse and keyboard for operation take up more space than
touch screen devices. Touch screen devices thus can be used with greater ease in areas where a user
does not have a lot of room to place a computer system.
The devices with keypads are susceptible to damage. For instance, a keyboard or a keypad has separate
keys and related circuits, any of which can break or become inoperable due to dirt, crumbs, water damage,
etc. In contrast, touch screens can be protected more easily because they do not have as many parts. This
means that touch screens have the potential to have a longer product life than standard monitors and
The fact that icons can be used with touch screens greatly increases the speed at which the user can
manipulate the system applications. It takes far less time for the brain to process an image than it does to
read an entire sentence of text, so users can go through the application processes in a matter of seconds
and be on their way faster. Speed also is increased because users don’t have to type out a response.
Touch screens have the potential to be more comfortable for the user. Impaired individuals can use touch-
screen technology, especially those who find using a mouse or keyboard difficult. For example, touch
screens often organize information in a clear and simplified way, so visually-impaired individuals can
operate them. Similarly, disabled patrons who have difficulty speaking or standing in long lines can take
advantage of touch-screen technology to access information easily and at their own pace. In addition,
touch-screen interfaces are often so easy to use that even people with little or no experience using
computers can operate one with minimal or no supervision. They also can be more accessible for those
with poor eyesight because icons sometimes can be easier to distinguish than text.
Easy User Interface
One of the major benefits of touch screens is the overall ease of use. Since the act of touching is instinctive,
touch-screen devices are relatively simple to operate. A clearly defined set of menus is easy to navigate
through when all the user has to do is touch the desired option. The user-friendly nature of the touch screen
also helps save time.
Easy to Clean and Maintain
Touch screen devices have smooth, flat screens, which makes cleaning a much easier task. Devices which
do not require a keyboard tend to collect less dust. The function of the computer mouse is eliminated as
well–a device with many crevices that are hard to clean. The wireless nature of the touch screen also
eliminates the mess of tangled power cords behind the desk.
Several businesses use touch-screen technology to accelerate their speed of service, allowing customers
to serve themselves at touch-screen kiosks. Customers use these self-serve kiosks for simple services,
such as purchasing movie tickets, paying bills or accessing account information quickly. As a result,
businesses can offer shorter lines and reduced wait times for other customers, while reducing the need to
hire, train and pay employees.
Thus we can conclude that Touch screen devices are user friendly and have many advantages that
will be beneficial for the Touch Screen users.
• Although user friendly, touch screen can not be used to enter large amount of data
• This technology has not found in real world applications because system designers have not carefully
considered how the system will function.
• Another failure of the industry has been not getting fast enough processing behind the buttons
• A touch screen system will cost about two or three times of the amount of an existing keyboard display.
Touch screen and monitors together are expensive ranging from two and half times the price of a