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ABSTRACT
TOUCH SCREEN
First computers became more visual, then they took a step further to
understand vocal commands and now they have gone a step further and
became ËœTOUCHYâ„¢, that is skin to screen.
A touchscreen is an easy to use input device that allows users to
control PC software and DVD video by touching the display screen. A
touch system consists of a touch Sensor that receives the touch input,
a Controller, and a Driver. The most commonly used touch technologies
are the Capacitive & Resistive systems. The other technologies used in
this field are Infrared technology, Near Field Imaging & SAW (surface
acoustic wave technology). These technologies are latest in this field
but are very much expensive.
The uses of touch systems as Graphical User Interface (GUI) devices for
computers continues to grow popularity. Touch systems are used for many
applications such as ATM™s, point-of“sale systems, industrial controls,
casinos & public kiosks etc. Touch system is basically an alternative
for a mouse or keyboard.
The market for touch system is going to be around $2.5 billion by 2004.
Various companies involved in development of touch systems mainly are
Philips, Samsung etc. Even touch screen mobile phones have been
developed by Philips.
INTRODUCTION
A touchscreen is an easy to use input device that allows users to
control PC software and DVD video by touching the display screen. We
manufacture and distribute a variety of touch screen related products.
A touch system consists of a touch
Sensor that receives the touch input, a Controller, and a Driver. The
touch screen sensor is a clear panel that is designed to fit over a PC.
When a screen is touched, the sensor detects the voltage change and
passes the signal to the touch screen controller. The controller that
reads & translates the sensor input into a conventional bus protocol
(Serial, USB) and a software driver which converts the bus information
to cursor action as well as providing systems utilities.
As the touch sensor resides between the user and the display while
receiving frequent physical input from the user vacuum deposited
transparent conductors serve as primary sensing element. Vacuum coated
layers can account for a significant fraction of touch system cost.
Cost & application parameters are chief criteria for determining the
appropriate type determining the system selection. Primarily, the touch
system integrator must determine with what implement the user will
touch the sensor with & what price the application will support.
Applications requiring activation by a
gloved finger or arbitrary stylus such as a plastic pen will specify
either a low cost resistive based sensor or a higher cost infra-red
(IR) or surface acoustic wave (SAW) system. Applications anticipating
bare finger input or amenable to a tethered pen comprises of the
durable & fast capacitive touch systems. A higher price tag generally
leads to increased durability better optical performance & larger
price.
The most commonly used systems are
generally the capacitive & resistive systems. The other technologies
used in this field are Infrared technology & SAW (surface acoustic wave
technology) these technologies are latest in this field but are very
much expensive.
How Does a Touchscreen Work?
A basic touchscreen has three main components: a touch
sensor, a controller, and a software driver. The touchscreen is an
input device, so it needs to be combined with a display and a PC or
other device to make a complete touch input system.
1.Touch Sensor
A touch screen sensor is a clear glass panel with a
touch responsive surface. The touch sensor/panel is placed over a
display screen so that the responsive area of the panel covers the
viewable area of the video screen. There are several different touch
sensor technologies on the market today, each using a different method
to detect touch input. The sensor generally has an electrical current
or signal going through it and touching the screen causes a voltage or
signal change. This voltage change is used to determine the location of
the touch to the screen.
2. Controller
The controller is a small PC card that connects
between the touch sensor and the PC. It takes information from the
touch sensor and translates it into information that PC can understand.
The controller is usually installed inside the monitor for integrated
monitors or it is housed in a plastic case for external touch add-
ons/overlays. The controller determines what type of
interface/connection you will need on the PC. Integrated touch monitors
will have an extra cable connection on the back for the touchscreen.
Controllers are available that can connect to a Serial/COM port (PC) or
to a USB port (PC or Macintosh). Specialized controllers are also
available that work with DVD players and other devices.
3.Software Driver
The driver is a software update for the
PC
system that allows the touchscreen and computer to work together. It
tells the computer's operating system how to interpret the touch event
information that is sent from the controller. Most touch screen drivers
today are a mouse-emulation type driver. This makes touching the screen
the same as clicking your mouse at the same location on the screen.
This allows the touchscreen to work with existing software and allows
new applications to be developed without the need for touchscreen
specific programming. Some equipment such as thin client terminals, DVD
players, and specialized computer systems either do not use software
drivers or they have their own built-in touch screen driver.
Comparing Touch Technologies
Each type of screen has unique characteristics that can make it a
better choice for certain applications.
The most widely used touchscreen technologies are the following:
4-Wire Resistive Touchscreens
4-Wire Resistive touch technology consists of a glass or acrylic
panel that is coated with electrically conductive and resistive layers.
The thin layers are separated by invisible separator dots. When
operating, an electrical current moves through the screen. When
pressure is applied to the screen the layers are pressed together,
causing a change in the electrical current and a touch event to be
registered.
4-Wire Resistive type touch screens are generally the
most affordable. Although clarity is less than with other touch screen
types, resistive screens are very durable and can be used in a variety
of environments. This type of screen is recommended for individual,
home, school, or office use, or less demanding point-of-sale systems,
restaurant systems, etc.
Advantages Disadvantages
¢ High touch resolution
¢ Pressure sensitive, works with any stylus
¢ Not affected by dirt, dust, water, or light
¢ Affordable touchscreen technology ¢ 75 % clarity
¢ Resistive layers can be damaged by a sharp object
¢ Less durable then 5-Wire Resistive technology
Touchscreen Specifications
Touch Type: 4-Wire Resistive
Screen Sizes: 12"-20" Diagonal
Cable Interface: PC Serial/COM Port or USB Port
Touch Resolution: 1024 x 1024
Response Time: 10 ms. maximum
Positional Accuracy: 3mm maximum error
Light Transmission: 80% nominal
Life Expectancy: 3 million touches at one point
Temperature: Operating: -10°C to 70°C
Storage: -30°C to 85°C
Humidity: Pass 40 degrees C, 95% RH for 96
hours.
Chemical Resistance: Alcohol, acetone, grease, and general household
detergent
Software Drivers: Windows XP / 2000 / NT / ME / 98 / 95, Linux,
Macintosh OS
5-Wire Resistive Touchscreens
5-Wire Resistive touch technology consists of a glass or
acrylic panel that is coated with electrically conductive and resistive
layers. The thin layers are separated by invisible separator dots. When
operating, an electrical current moves through the screen. When
pressure is applied to the screen the layers are pressed together,
causing a change in the electrical current and a touch event to be
registered.
5-Wire Resistive type touch screens
are generally more durable than the similiar 4-Wire Resistive type.
Although clarity is less than with other touch screen types, resistive
screens are very durable and can be used in a variety of environments.
This type of screen is recommended for demanding point-of-sale systems,
restaurant systems, industrial controls, and other workplace
applications.
Advantages Disadvantages
¢ High touch resolution
¢ Pressure sensitive, works with any stylus
¢ Not affected by dirt, dust, water, or light
¢ More durable then 4-Wire Resistive technology ¢ 75 %
clarity
¢ Resistive layers can be damaged by a sharp object
Touchscreen Specifications
Touch Type: 5-Wire Resistive
Cable Interface: PC Serial/COM Port or USB Port
Touch Resolution: 4096 x 4096
Response Time: 21 ms.
Light Transmission: 80% +/-5% at 550 nm wavelength (visible light
spectrum)
Expected Life: 35 million touches at one point
Temperature: Operating: -10°C to 50°C
Storage: -40°C to 71°C
Humidity: Operating: 90% RH at max 35°C
Storage: 90% RH at max 35°C for 240
Chemical Resistance: Acetone, Methylene chloride, Methyl ethyl
ketone , Isopropyl alcohol, Hexane, Turpentine, Mineral spirits,
Unleaded Gasoline, Diesel Fuel, Motor Oil, Transmission Fluid,
Antifreeze, Ammonia based glass cleaner, Laundry Detergents, Cleaners
(Formula 409, etc.), Vinegar, Coffee, Tea, Grease, Cooking Oil, Salt
Software Drivers: Windows XP, 2000, NT, ME, 98, 95, 3.1, DOS,
Macintosh OS, Linux, Unix (3rd Party)
Capacitive Touchscreens
A capacitive touch screen consists of a glass panel with a capacitive
(charge storing) material coating its surface. Circuits located at
corners of the screen measure the capacitance of a person touching the
overlay. Frequency changes are measured to determine the X and Y
coordinates of the touch event.
Capacitive type touch screens are
very durable, and have a high clarity. They are used in a wide range of
applications, from restaurant and POS use to industrial controls and
information kiosks.
Advantages Disadvantages
¢ High touch resolution
¢ High image clarity
¢ Not affected by dirt, grease, moisture. ¢ Must be
touched by finger, will not work with any non-conductive input
Touchscreen Specifications
Touch Type: Capacitive
Cable Interface: PC Serial/COM Port (9-pin) or USB Port
Touch Resolution: 1024 x 1024
Light Transmission: 88% at 550 nm wavelength (visible light
spectrum)
Durability Test: 100,000,000 plus touches at one point
Temperature: Operating: -15°C to 50°C
Storage: -50°C to 85°C
Humidity: Operating: 90% RH at max 40°C, non-condensing
Chemical Resistance: The active area of the touchscreen is resistant
to all chemicals that do not affect glass, such as: Acetone, Toluene,
Methyl ethyl ketone, Isopropyl alcohol, Methyl alcohol, Ethyl acetate,
Ammonia-based glass cleaners, Gasoline, Kerosene, Vinegar
Software Drivers: Windows XP, 2000, NT, ME, 98, 95, 3.1, DOS,
Macintosh OS, Linux, Unix (3rd Party)
PenTouch Capacitive Touchscreens
PenTouch Capacitive touchscreen technology works with the CRT and LCD
touch monitors. This screen combines durable Capacitive technology with
a tethered pen stylus. The screen can be set to respond to finger input
only, pen input only, or both. The pen stylus is a good choice for
signature capture, on-screen annotations, or for applications requiring
precise input.

Surface Acoustic Wave Touchscreens

Surface Acoustic Wave technology is one of the most advanced touch
screen types. It is based on sending acoustic waves across a clear
glass panel with a series of transducers and
reflectors. When a finger touches the screen, the waves are absorbed,
causing a touch event to be detected at that point.
Because the panel is all glass there are no
layers that can be worn, giving this technology the highest durability
factor and also the highest clarity. This technology is recommended for
public information kiosks, computer based training, or other high
traffic indoor environments.
Advantages Disadvantages
¢ High touch resolution
¢ Highest image clarity
¢ All glass panel, no coatings or layers that can wear out or
damage ¢ Must be touched by finger, gloved hand, or soft-tip
stylus. Something hard like a pen won't work
¢ Not completely sealable, can be affected by large amounts of
dirt, dust, and / or water in the environment.
Near Field Imaging Touchscreens
NFI is one of the newest technologies. It consists of two laminated
glass sheets with a patterned coating of transparent metal oxide in
between. An AC signal is applied to the patterned conductive coating,
creating an electrostatic field on the surface of the screen. When the
finger or glove or other conductive stylus comes into contact with the
sensor, the electrostatic field is disturbed. It is an extremely
durable screen that is suited for use in industrial control systems and
other harsh environments. The NFI type screen is not affected by most
surface contaminants or scratches. Responds to finger or gloved hand.
Infrared Touchscreens
Infrared touch screen monitors are based on light-beam interruption
technology. A frame surrounds the displayâ„¢s surface. The frame has
light sources, or light-emitting diodes (LEDs),on one side, and light
detectors on the opposite side. This design creates an optical grid
across the screen. When any object touches the screen, the invisible
light beam is interrupted, causing a drop in the signal received by the
photo sensors. One concern with this technology is that it might
respond to a very light touch, even that of an insect crossing the
monitor, making unwanted system adjustments. This is the only type of
touch technology that are available for large displays such as 42-inch
Plasma screens. It is a durable technology that offers high image
clarity. Responds to any input device or stylus.
Information Kiosk Systems
A Kiosk (pronounced key-osk) is a computer based terminal or display
that is used to provide information or services, typically in a public
place. Kiosk systems are being used in a variety of applications,
including information directories, customer self-service terminals,
electronic catalogs, internet access terminals, tourism guides, and
more.
Complete Kiosk Systems
Several affordable and easy to use kiosk enclosures are available with
integrated touch screen monitors. Available with several of the leading
touchscreen technologies and with a variety of laminate, stained oak,
and painted metal finishes.
Mountable Monitors for Kiosk Systems
A variety of mountable
displays that can be used in kiosk applications, including mountable
CRT monitors and several types of mountable flat panel monitors are
available.
Other Components for Kiosk Systems
A variety of hardware
components that can be used in information kiosk systems, including
mountable printer, fan, and speaker grills are available.
Software for Kiosk Systems
Several software packages can
be used in a kiosk environment, including a presentation development
package and an on-screen keyboard package.
Software, Cables, and Accessories
Software:
Touchscreen related software, including presentation development
software and other utilities
1. MYTSOFT
My-T-Soft On-Screen Keyboard Software
2. RIGHTTOUCH
RightTouch Right-Click Utility Software

MYTSOFT
My-T-Soft On-Screen Keyboard Software
My-T-Soft is an On-Screen keyboard utility that works with any Windows
95 / 98 / Me / NT / 2000 / XP software. It provides on-screen keyboards
and user programmable buttons that allow users to enter data using a
touchscreen display.
My-T-Soft can be used by itself in home or workplace applications, and
it includes a developer's kit that allows the keyboard to be called up
from Web pages and other programs.
By allowing systems to operate without the need for a physical
keyboard, external templates, membranes, or buttons, My-T-Soft can
provide the finishing touch on sealed systems that only require a
touchscreen for user input.
My-T-Soft uses a concept called "Heads Up Display" technology and its
principal objective is to keep the users focus and concentration
centered in one place. My-T-Soft uses that concept to reduce the visual
re-focusing and re-positioning caused by the
head's up and down motion of going from screen to keyboard to screen.
Features:
Over 40 "Heads-Up Display" Keyboards with 12 base
sizes and infinitely larger sizes
ABCD Alphabetical, QWERTY, 3 DVORAK's, and over 40
International (German, Spanish, French, etc.) with Edit and Numeric
panels.
Store up to 2000 keystrokes/menu selections (or the applications macro
scripts) on each button. Up to 15 buttons can be grouped on individual
Panels, which auto-open when their assigned application becomes active.
Developer friendly
Show & Hide keys, program keys in Key
Options, Custom logo display, Operator mode, on-demand functionality.
The Developer's Kit comes with all kinds of utilities, source code,
sample code, and a wealth of information for integrating My-T-Soft with
your own application. Assignable Functions for Pointing Device Buttons
RIGHTTOUCH
RightTouch Right-Click Utility Software
An easy interface to bring Right Click capability to any touchscreen.
Most touchscreens work by emulating left mouse button clicks, so that
touching the screen is the same as clicking your left mouse button at
that same point on the screen. But what if you need to right click on
an item? Some touchscreens do include right click support, but many do
not. The Right Touch utility provides an easy way to perform right
clicks with any touchscreen.
The Right Touch utility places a button on your desktop that allows you
to switch the touchscreen between left and right clicks. When the
screen is emulating left clicks, simply touch the Right Touch button to
change to right click mode. Touch again, and you're back to the
standard left click.
Software Requirements
Windows95/98/ME/NT/2000/XP
Please Note: Many of the touchscreen systems include a similar right-
click tool with their software driver. The Right-Touch software is
useful for touchscreens that do not have an included right click
utility.
Cables:
Cables for use with the touch monitors, includes video and serial port
extension cables.
Serial Cables
SERIAL25: 25-Foot Serial Extension Cable
SERIAL50: 50-Foot Serial Extension Cable
SERIAL100: 100-Foot Serial Extension

VGA Video Cables
VGA25: 25-Foot VGA Extension Cable
VGA50: 50-Foot VGA Extension Cable
VGA100: 100-Foot VGA Extension Cable

VGA-Y: VGA Video Y-Splitter Cable



Accessories:
Stylus Pens
A stylus pen can be used along with our touchscreen systems for precise
input.
STYLUS1
Stylus Pen for Resistive Touchscreens

STYLUS2
Stylus Pen for Surface Acoustic Wave

Touchscreens


Touch Screen Drivers
UPD Driver 3.5.18
These drivers are for 3M Dynapro SC3 and SC4 Controllers
The new UPD Driver will work for the following controllers: SC3 Serial,
SC4 Serial, SC4 USB. Supported platforms are Win2000/WinNT/Win9x/Me/XP.
DOS and other drivers
Linux Drivers for SC3 and SC4 Controllers
Linux drivers for SC3 and SC4 were developed by a third party, not 3M
Touch Systems, and are provided for our customers convenience. 3M Touch
Systems cannot offer any warranty or technical support for them.
Linux Drivers
TouchWare Driver, Release 5.63 SR3
These drivers are for MicroTouch Touch Controllers (EXII, SMT3, MT3000,
MT410, MT510)
This release improves performance for Windows XP drivers. It provides
multiple monitor support, including dual head video adapters, from
TouchWare 5.63. Supported platforms are WinXP/Win2000/WinNT/Win9x/Me.
This service release also corrects known problems with silent
installation.
Microcal 7.1
Use this utility to modify controller settings and to calibrate the
sensor at different resolutions under DOS. Microcal is compatible with
fully-integrated ClearTek capacitive and TouchTek resistive
touchscreens. This release supports any serial and PS/2 SMT controller,
PC BUS controllers and the MT400 controller.
Near Field Imaging OEM Drivers
Use the OEM drivers below with Near Field Imaging touch screen
products.
For Windows NT/9X:
8.4-inch Near Field Imaging touch screens (approx. 2.5MB)
For Windows NT/9X/3.1 and MS-DOS:
10.4-inch and larger Near Field Imaging touch screens (approx> 3.6MB)
For Windows XP/2000 for 10.4-inch and larger Near Field Imaging touch
screens
Linux Drivers for NFI
Linux drivers for NFI were developed by a third party, not 3M Touch
Systems, and are provided for our customers' convenience. 3M Touch
Systems cannot offer any warranty or technical support for them.
APPLICATIONS
The touch screen is one of the easiest PC interfaces to use, making it
the interface of choice for a wide variety of applications. Here are a
few examples of how touch input systems are being used today:
1. Public Information Displays
Information kiosks, tourism displays, trade show displays, and other
electronic displays are used by many people that have little or no
computing experience. The user-friendly touch screen interface can be
less intimidating and easier to use than other input devices,
especially for novice users. A touchscreen can help make your
information more easily accessible by allowing users to navigate your
presentation by simply touching the display screen
2. Retail and Restaurant Systems
Time is money, especially in a fast paced retail or restaurant
environment. Touchscreen systems are easy to use so employees can get
work done faster, and training time can be reduced for new employees.
And because input is done right on the screen, valuable counter space
can be saved. Touchscreens can be used in cash registers, order entry
stations, seating and reservation systems, and more
3. Customer Self-Service
In today's fast pace world, waiting in line is one of the things that
has yet to speed up. Self-service touch screen terminals can be used to
improve customer service at busy stores, fast service restaurants,
transportation hubs, and more. Customers can quickly place their own
orders or check themselves in or out, saving them time, and decreasing
wait times for other customers. Automated bank teller (ATM) and airline
e-ticket terminals are examples of self-service stations that can
benefit from touchscreen input.
4. Control and Automation Systems
The touch screen interface is useful in systems ranging from industrial
process control to home automation. By integrating the input device
with the display, valuable workspace can be saved. And with a graphical
interface, operators can monitor and control complex operations in
real-time by simply touching the screen.
5. Computer Based Training
Because the touch screen interface is more user-friendly than other
input devices, overall training time for computer novices, and
therefore training expense, can be reduced. It can also help to make
learning more fun and interactive, which can lead to a more beneficial
training experience for both students and educators.
6. Assistive Technology
The touch screen interface can be beneficial to those that have
difficulty using other input devices such as a mouse or keyboard. When
used in conjunction with software such as on-screen keyboards, or other
assistive technology, they can help make computing resources more
available to people that have difficulty using computers.
Take a look at how one of our customers, CHI Centers, Inc., has
developed a system that allows non-verbal individuals to communicate
using a PC and touchscreen display.
ADVANTAGES OVER OTHER POINTING DEVICES
Touch screens have several advantages over other pointing devices:
¢ Touching a visual display of choices requires little thinking
and is a form of direct manipulation that is easy to learn.
¢ Touch screens are the fastest pointing devices.
¢ Touch screens have easier hand eye coordination than mice or
keyboards.
¢ No extra work space is required as with other pointing devices.
¢ Touch screens are durable in public access and in high volume
usage.
Disadvantages
¢ User™s hand may obscure the screen.
¢ Screens need to be installed at a lower position and tilted to
reduce arm fatigue.
¢ Some reduction in image brightness may occur.
¢ They cost more than alternative devices.
Conclusion
Touch systems represent a rapidly growing subset of the display market.
The majority of touch systems include touch sensors relying on vacuum-
deposited coatings, so touch coatings present opportunity for suppliers
of vacuum coatings and coating equipments.
Touch sensor manufactures currently require thin films in the areas of
transparent conductors, optical interference coating and mechanical
protective coatings. Touch sensors technical requirements dovetail well
with those of the flat panel and display filter markets. The reality
should provide value added opportunities to operations participating in
these areas.

INDEX
1. Abstract
2. Introduction
3. How Does a Touchscreen Work?
4. Comparing Touch Technologies.
5. Information Kiosk Systems.
6. Software, Cables, and Accessories.
7. Touchscreen Drivers.
8. Applications.
9. Advantages over other pointing devices.
10. Conclusion.

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Abstract
[TOUCH SCREEN] A touch screen is an easy to use input device that allows users to control PC software and DVD video by touching the display screen. A touch screen can be used with most PC systems as easily as other input devices such as track balls or touch pads.
1.1. Defination
A touchscreen is an electronic visual display that can detect the presence and location of a touch within the display area. The term generally refers to touch or contact to the display of the device by a finger or hand. Touchscreens can also sense other passive objects, such as a pen. However, if the object sensed is active, as with a light pen, the term touchscreen is generally not applicable. The ability to interact physically with what is shown on a display (a form of "direct manipulation") typically indicates the presence of a touchscreen.
The touchscreen has two main attributes. First, it enables one to interact with what is displayed directly on the screen, where it is displayed, rather than indirectly with a mouse or touchpad. Secondly, it lets one do so without requiring any intermediate device, again, such as a stylus that needs to be held in the hand. Such displays can be attached to computers or, as terminals, to networks. They also
play a prominent role in the design of digital appliances such as the personal digital assistant (PDA),satellite navigation devices, mobile phones, and video games.

1.2. History
Touchscreens emerged from academic and corporate research labs in the second half of the 1960s. One of the first places where they gained some visibility was in the terminal of a computer-assisted learning terminal that came out in 1972 as part of the PLATO project. They have subsequently become familiar in kiosk systems, such as in retail and tourist settings, on point of sale systems, on ATMs and on PDAs where a stylus is sometimes used to manipulate the GUI and to enter data. The popularity of smart phones, PDAs, portable game consoles and many types of information appliances is driving the demand for, and the acceptance of, touchscreens. The HP-150 from 1983 was probably the world's earliest commercial touchscreen computer. It did not actually have a touchscreen in the strict sense, but a 9" Sony CRT surrounded by infrared transmitters and receivers which detect the position of any non-transparent object on the screen. Until the early 1980s, most consumer touchscreens could only sense one point of contact at a time, and few have had the capability to sense how hard one is touching. This is starting to change with the commercialisation of multi-touch technology. Touchscreens are popular in heavy industry and in other situations, such as museum displays or room
automation, where keyboard and mouse systems do not allow a satisfactory, intuitive, rapid, or accurate interaction by the user with the display's content. Historically, the touchscreen sensor and its accompanying controller-based firmware have been made available by a wide array of after-market system integrators and not by display, chip or motherboard manufacturers. With time, however, display manufacturers and chip manufacturers worldwide have acknowledged the trend toward acceptance of touchscreens as a highly desirable user interface component and have begun to integrate touchscreen functionality into the fundamental design of their products.

1.3. Why Touch Technology

1. Touch screens enable people to use computers instantly, without any training whatsoever.
2. Touch screens virtually eliminate operator errors because users select from clearly defined menus.
3. Touch screens eliminate keyboards and mice, which many find intimidating and cumbersome to use.
4. Touch screens are rugged enough to stand up to harsh environments where keyboards and mice often get damaged.
5. Touch screens provide fast access to any and all types of digital media, with no text-bound interface getting in the way.
6. Touch screens ensure that no space - on the desktop or elsewhere - is wasted, as the input device is completely integrated in to the monitors.

1.4 How Does Touch Screen Works

1. Touch Screen Sensor: It is a clear glass panel with a touch responsive surface. The touch sensor/panel is placed over a display screen so that the responsive area of the panel covers the viewable area of the video screen.
2. Controller: I t is a small PC card that connects between the touch sensor and the PC. It takes information from the touch sensor and translates it into information that PC can understand.
3. Software Driver: The driver is a software update for the PC system that allows the touch screen and computer to work together. It tells the computer's operating system how to interpret the touch event information that is sent from the controller.
2. Construction
There are several principal ways to build a touchscreen. The key goals are to recognize one or more fingers touching a display, to interpret the command that this represents, and to communicate the command to the appropriate application.
In the most popular techniques, the capacitive or resistive approach, there are typically four layers;
1. Top polyester layer coated with a transparent metallic conductive coating on the bottom
2. Adhesive spacer
3. Glass layer coated with a transparent metallic conductive coating on the top
4. Adhesive layer on the backside of the glass for mounting.
When a user touches the surface, the system records the change in the electrical current that flowsthrough the display.
Dispersive-signal technology which 3M created in 2002, measures the piezoelectric effect ” the voltage generated when mechanical force is applied to a material ” that occurs chemically when a strengthened glass substrate is touched.
There are two infrared-based approaches. In one, an array of sensors detects a finger touching or almost touching the display, thereby interrupting light beams projected over the screen. In the other, bottommounted infrared cameras record screen touches.
In each case, the system determines the intended command based on the controls showing on the screen at the time and the location of the touch.
3. Technologies
3.1. Resistive
A resistive touchscreen panel is composed of several layers, the most important of which are two thin, metallic, electrically conductive layers separated by a narrow gap. When an object, such as a finger, presses down on a point on the panel's outer surface the two metallic layers become connected at that point: the panel then behaves as a pair of voltage dividers with connected outputs. This causes a change in the electrical current which is registered as a touch event and sent to the controller for processing.

3.2. Surface Acoustic Wave
Surface acoustic wave (SAW) technology uses ultrasonic waves that pass over the touchscreen panel. When the panel is touched, a portion of the wave is absorbed. This change in the ultrasonic waves registers the position of the touch event and sends this information to the controller for processing. Surface wave touch screen panels can be damaged by outside elements. Contaminants on the surface can also interfere with the functionality of the touchscreen.
3.3. Capacitve
A capacitive touchscreen panel consists of an insulator such as glass, coated with a transparent conductor such as indium tin oxide (ITO). As the human body is also a conductor, touching the surface of the screen results in a distortion of the body's electrostatic field, measurable as a change in capacitance. Different technologies may be used to determine the location of the touch. The location can be passed to a computer running a software application which will calculate how the user's touch relates to the computer software.
3.3.1. Surface capacitance
In this basic technology, only one side of the insulator is coated with a conductive layer. A small voltage is applied to the layer, resulting in a uniform electrostatic field. When a conductor, such as a human finger, touches the uncoated surface, a capacitor is dynamically formed. The sensor's controller can determine the location of the touch indirectly from the change in the capacitance as measured from the
four corners of the panel. As it has no moving parts, it is moderately durable but has limited resolution, is prone to false signals from parasitic capacitive coupling, and needs calibration during manufacture. It is therefore most often used in simple applications such as industrial controls and kiosks.
3.3.2. Projected capacitance
Projected Capacitive Touch (PCT) technology is a capacitive technology which permits more accurate and flexible operation, by etching the conductive layer. An XY array is formed either by etching a single layer to form a grid pattern of electrodes, or by etching two separate, perpendicular layers of conductive material with parallel lines or tracks to form the grid (comparable to the pixel grid found in many LCD
displays).
Applying voltage to the array creates a grid of capacitors. Bringing a finger or conductive stylus close to the surface of the sensor changes the local electrostatic field. The capacitance change at every individual point on the grid can be measured to accurately determine the touch location. The use of a grid permits a higher resolution than resistive technology and also allows multi-touch operation. The greater resolution of PCT allows operation without direct contact, such that the conducting layers can be coated with further protective insulating layers, and operate even under screen protectors, or behind weather and vandal-proof glass. However, conductive smudges and the like can seriously interfere with the resolution, making multiple touches necessary to get the desired functionality. Such conductive smudges come mostly from sticky or sweaty finger tips, especially in high humidity environments. Collected dust, which adheres to the screen due to the moisture from fingertips, is a serious drawback for the longlife operation of PCT.
PCT is used in a wide range of applications including point of sale systems, smartphones, and public information kiosks. Visual Planet's ViP Interactive Foil is an example of a kiosk PCT product, where a gloved hand can register a touch on a sensor surface through a glass window. Examples of consumer devices using projected capacitive touchscreens include Apple Inc.'s iPhone and iPod Touch, HTC's HD2, G1, and HTC Hero, Motorola's Droid, Palm Inc.'s Palm Pre and Palm Pixi and more recently the LG KM900 Arena, Microsoft's Zune HD, Sony Walkman X series, Sony Ericsson's Aino and now Vidalco's Edge, D1 and Jewel, the Nokia X6 phone and Google's Nexus One.
3.4. Strain Gauge
In a strain gauge configuration, also called force panel technology, the screen is spring-mounted on the four corners and strain gauges are used to determine deflection when the screen is touched. This technology has been around since the 1960s but new advances by Vissumo and F-Origin have made the solution commercially viable. It can also measure the Z-axis and the force of a person's touch. Such screens are typically used in exposed public systems such as ticket machines due to their resistance to vandalism.
3.5. Optical Imaging
A relatively-modern development in touchscreen technology, two or more image sensors are placed around the edges (mostly the corners) of the screen. Infrared backlights are placed in the camera's field of view on the other sides of the screen. A touch shows up as a shadow and each pair of cameras can then be triangulated to locate the touch or even measure the size of the touching object (see visual hull). This technology is growing in popularity, due to its scalability, versatility, and affordability, especially
for larger units.

3.6. Dispersive Signal Technology
Introduced in 2002 by 3M, this system uses sensors to detect the mechanical energy in the glass that occurs due to a touch. Complex algorithms then interpret this information and provide the actual location of the touch. The technology claims to be unaffected by dust and other outside elements, including scratches. Since there is no need for additional elements on screen, it also claims to provide excellent optical clarity. Also, since mechanical vibrations are used to detect a touch event, any object can be used to generate these events, including fingers and stylus. A downside is that after the initial touch the system cannot detect a motionless finger.
3.7. Acoustic Pulse Recognition
This system, introduced by Tyco International's Elo division in 2006, uses more than two piezoelectric transducers located at some positions of the screen to turn the mechanical energy of a touch (vibration) into an electronic signal. The screen hardware then uses an algorithm to determine the location of the touch based on the transducer signals. This process is similar to triangulation used in GPS. The touchscreen itself is made of ordinary glass, giving it good durability and optical clarity. It is usually able to function with scratches and dust on the screen with good accuracy. The technology is also well suited to displays that are physically larger. As with the Dispersive Signal Technology system, after the initial touch, a motionless finger cannot be detected. However, for the same reason, the touch recognition is not disrupted by any resting objects.

3.8. Coded LCD
A new system that turns LCD displays into giant cameras that provide gestural control of objects onscreen was introduced by MIT Media Lab in December, 2009. Instead of an LCD, an array of pinholes is placed in front of sensors. Light passing through each pinhole strikes a small block of sensors producing a low-resolution image. Since each pinhole image is taken from a slightly different position, all combined images provide a good depth information about the sensed image.
Pinholes are problematic because they allow very little light to reach the sensors, requiring impractically long exposure times. Instead of pinholes, an array of liquid crystals could work similarly but more effectively: The LCD's panel is composed of patterns of 19-by-19 blocks, each divided into a regular pattern of differently sized black-and-white rectangles. Each white area of the bi-colored pixels allows light to pass through. Background software uses 4D light fields to calculate depth map, changes the scene, and collects gesture information. The LCD alternates between mask pattern display and a normal scene display at a very high frequency/rate.
4. Development
Virtually all of the significant touchscreen technology patents were filed during the 1970s and 1980s and have expired. Touchscreen component manufacturing and product design are no longer encumbered by royalties or legalities with regard to patents and the manufacturing of touchscreen-enabled displays on all kinds of devices is widespread.
The development of multipoint touchscreens facilitated the tracking of more than one finger on the screen, thus operations that require more than one finger are possible. These devices also allow multiple users to interact with the touchscreen simultaneously.
With the growing acceptance of many kinds of products with an integral touchscreen interface the marginal cost of touchscreen technology is routinely absorbed into the products that incorporate it and is effectively eliminated. As typically occurs with any technology, touchscreen hardware and software has sufficiently matured and been perfected over more than three decades to the point where its reliability is unassailable. As such, touchscreen displays are found today in airplanes, automobiles, gaming consoles, machine control systems, appliances and handheld display devices of every kind. With the influence of the multi-touch-enabled iPhone, the touchscreen market for mobile devices is projected to produce US$5 billion in 2009.
The ability to accurately point on the screen itself is taking yet another step with the emerging graphics tablet/screen hybrids.
5. Ergonomic And Usage
5.1. Finger stress
An ergonomic problem of touchscreens is their stress on human fingers when used for more than a few minutes at a time, since significant pressure can be required for certain types of touchscreen. This can be alleviated for some users with the use of a pen or other device to add leverage and more accurate pointing. However, the introduction of such items can sometimes be problematic depending on the desired use case (for example, public kiosks such as ATMs). Also, fine motor control is better achieved with a stylus, because a finger is a rather broad and ambiguous point of contact with the screen itself.
5.2. Fingernail as stylus
These ergonomic issues of direct touch can be bypassed by using a different technique, provided that the user's fingernails are either short or sufficiently long. Rather than pressing with the soft skin of an outstretched fingertip, the finger is curled over, so that the top of the forward edge of a fingernail can be used instead. (The thumb is optionally used to provide support for the finger or for a long fingernail, from underneath.)
The fingernail's hard, curved surface contacts the touchscreen at a single very small point. Therefore, much less finger pressure is needed, much greater precision is possible (approaching that of a stylus, with a little experience), much less skin oil is smeared onto the screen, and the fingernail can be silently moved across the screen with very little resistance, allowing for selecting text, moving windows, or drawing lines.
The human fingernail consists of keratin which has a hardness and smoothness similar to the tip of a stylus (and so will not typically scratch a touchscreen). Alternately, very short stylus tips are available, which slip right onto the end of a finger; this increases visibility of the contact point with the screen. Oddly, with capacitive touchscreens, the reverse problem applies in that individuals with long nails have reported problems getting adequate skin contact with the screen to register keystrokes. Ordinary styluses do not work on capacitive touchscreens nor do fingers gloved in insulating materials. There do exist conductive gloves that are specially designed to allow the user to interact with capacitive sensors.
5.3. Fingerprints
Touchscreens can suffer from the problem of fingerprints on the display. This can be mitigated by the use of materials with optical coatings designed to reduce the visible effects of fingerprint oils, such as the oleophobic coating used in the iPhone 3G S, or by reducing skin contact by using a fingernail or stylus.
5.4. Combined with haptics
The user experience with touchscreens without tactile feedback or haptics can be difficult due to latency or other factors. Research from the University of Glasgow Scotland [Brewster, Chohan, and Brown 2007] demonstrates that sample users reduce input errors (20%), increase input speed (20%), and lower their cognitive load (40%) when touchscreens are combined with haptics or tactile feedback, [vs. nonhaptic touchscreens].
Technology
4-Wire
SAW
5-Wire
Infrared
Capacitive
Durability:
3 year
5 Year
5 Year
5 Year
2 Year
Stability:
High
Higher
High
High
Ok
Transparency:
Bad
Good
Bad
Good
Ok
Installation:
Built in/
Onwall
Built in/
Onwall
Built in/
Onwall
Onwall
Built-in
Touch:
Anything
Finger/Pen
Anything
Finger/Pen
Conductive
Intense
Light resistant:
Good
Good
Good
Bad
Bad
Response time:
<10ms
10ms
<15ms
<20ms
<15ms
Following Speed:
Good
low
Good
Good
Good
Excursion:
No
Small
Big
Big
Big
Monitor option:
CRT or LCD
CRT or LCD
CRT or LCD
CRT or LCD
CRT or LCD
Waterproof:
Good
Ok
Good
Ok
Good
6. Comparision Of Touchscreen Technology
7. Advantages
1. Big screen is ideal for web browsing, picture and movies.
2. Touchscreen gadgets usually have simple user interfaces, which are more intuitive (iPhone once again is a good example).
3. Touchscreen devices have fewer buttons that might break after a few months/years of operation.
8. Disadvantages
1. Screen has to be really big not to miss things when pressing them with your finger.
2. Big screen leads to low battery life.
3. Touchscreen means screen canâ„¢t be read too well in direct sunlight as it applies an additional not 100% transparent.
4. Touchscreen devices usually has no additional keys (see the iPhone) and this means when an app crashes, without crashing the OS, you canâ„¢t get to the main menu as the whole screen becomes unresponsive.
5. Touchscreens usually have low precision, virtual QWERTY keyboards being one of the most annoying things.
6. Most user interfaces are not optimized for thumb operation, so a stylus in necessary, and this means using two hands.
7. Screens get very dirty.
8. These devices require massive computing power which leads to slow devices and low battery life.
9. Applications
9.1 Public Information Displays
Tourism displays, trade show displays, and other electronic displays are used by many people that have little or no computing experience.

9.2 Customer self-service
Customers can quickly place their own orders or check themselves in or out, saving them time, and decreasing wait times for other customers. Example: ATM
9.3 Computer Based Training
Since the touch screen interface is more user-friendly than other input devices, overall training time for computer novices and therefore training expense can be reduced. Also make learning more interactive and fun.
9.4 Other applications
Include computerized gaming, student registration systems, financial and scientific applications.
10. Benefits
1. Fast, faster, fastest
2. Touch makes everyone an expert
3. Reduced cost
4. Compact & handy
5. Durable and easy to clean
6. When ease of use is required
11. Conclusion
A touch screen is the simplest, most direct way for a person to interact with a computer. The basic way users interact with a touch screen is age-old. You point to what you want. It's intuitive for virtually every child and adult in the world today.

TOUCH SCREEN
CONTENTS
1. Introduction
1.1. Defination
1.2. History
1.3. Why Touch Technology
1.4. How Does Touch Screen Works
2. Construction
3. Technologies
3.1. Resistive
3.2. Surface Acoustic Wave (SAW)
3.3. Capacitive
3.4. Strain Gauge
3.5. Optical Imaging
3.6. Dispersive Signal Technology
3.7. Acoustic Pulse Recognition
3.8. Coded LCD
4. Development
5. Ergonomics And Usage
6. Comparision Of Touch Screen Technologies
7. Advantages
8. Disadvantages
9. Applications
10. Benefits
11. Conclusion
1. INTRODUCTION

These links have more reports and ppt of the topic:
http://scribddoc/28894552/Touch-Screen-Technology-1
http://scribddoc/21138453/Touch-Screen-Technology
http://scribddoc/18666348/Touch-Screen-Technology

[attachment=4100]
TOUCH SCREEN
Definition
A touch screen is a computer display screen that is sensitive to human touch, allowing a user to interact with the computer by touching pictures or words on the screen.
Touch screen technology can be used as an alternative user interface with applications that normally require a mouse, such as a Web browser.
Some applications are designed specifically for touch screen technology, often having larger icons and links than the typical PC application.
Monitors are available with built-in touch screen technology or individuals can purchase a touch screen kit.

Touchscreen
Introduction
A Touchscreen is a display which can detect the location of touches within the display area. This allows the display to be used as an input device
mouse as the removing the keyboard and/or the primary input device for interacting with the display's content
Such displays can be attached to computers or, as terminals, to networks. Touchscreens also have assisted in recent changes in the design of personal digital assistant (PDA), satellite navigation and mobile phone devices, making these devices more usable.
Application

Touchscreens have become commonplace since the invention of the electronic touch interface in 1971 by Dr. Samuel C. Hurst.
They have become familiar in retail settings, on point of sale systems, on ATMs and on PDAs(personal digital assistant) sometimes used to manipulate the GUI and to enter data.
The HP-150 from 1983 was probably the world's earliest commercial touch screen computer.
It actually does not have a touch screen in the strict sense, but a 9" Sony CRT surrounded by infrared transmitters and receivers which detect the position of any non-transparent object on the screen.



Touchscreens are popular in heavy industry and in other situations, such as museum displays or room automation, where keyboards and mouse do not allow a satisfactory
the touchscreen sensor and its accompanying controller-based firmware have been made available by a wide array of after-market system integrators and not by display, chip or motherboard manufacturers
With time,display manufacturers and System On Chip (SOC) manufacturers worldwide have acknowledged the trend toward acceptance of touchscreens as a highly desirable user interface component and have begun to integrate touchscreen functionality into the fundamental design of their products.

A touch screen kit includes a touch screen panel, a controller, and a software driver.
The touch screen panel is a clear panel attached externally to the monitor that plugs into a serial or Universal Serial Bus (USB) port or a bus card installed inside the computer.
The touch screen panel registers touch events and passes these signals to the controller.
The controller then processes the signals and sends the data to the processor.
The software driver translates touch events into mouse events.
Drivers can be provided for both Windows and Macintosh operating systems.
Internal touch screen kits are available but require professional installation because they must be installed inside the monitor
Technology

Most Common types Of Touchscreen Technology
1. Resistive
2. Surface acoustic wave
3. Capacitive
4. Dispersive signal technology
5. Acoustic pulse recognition


Resistive
Resistive: A resistive touch screen panel is coated with a thin metallic electrically conductive and resistive layer that causes a change in the electrical current which is registered as a touch event and sent to the controller for processing. Resistive touch screen panels are generally more affordable but offer only 75% clarity and the layer can be damaged by sharp objects. Resistive touch screen panels are not affected by outside elements such as dust or water.

Surface acoustic wave
Surface wave: Surface wave technology uses ultrasonic waves that pass over the touch screen panel. When the panel is touched, a portion of the wave is absorbed. This change in the ultrasonic waves registers the position of the touch event and sends this information to the controller for processing. Surface wave touch screen panels are the most advanced of the three types, but they can be damaged by outside elements.

Capacitive
Capacitive: A capacitive touch screen panel is coated with a material that stores electrical charges. When the panel is touched, a small amount of charge is drawn to the point of contact. Circuits located at each corner of the panel measure the charge and send the information to the controller for processing. Capacitive touch screen panels must be touched with a finger unlike resistive and surface wave panels that can use fingers and stylus. Capacitive touch screens are not affected by outside elements and have high clarity.

Dispersive signal technology
Dispersive signal technology : Introduced in 2002, this system uses sensors to detect the mechanical energy in the glass that occur due to a touch.
Complex algorithms then interpret this information and provide the actual location of the touch.
The technology claims to be unaffected by dust and other outside elements, including scratches. Since there is no need for additional elements on screen, it also claims to provide excellent optical clarity.
Also, since mechanical vibrations are used to detect a touch event, any object can be used to generate these events, including fingers and styli.
A downside is that after the initial touch the system cannot detect a motionless finger.

Acoustic pulse recognition
Acoustic pulse recognition : This system uses more than two piezoelectric transducers located at some positions of the screen to turn the mechanical energy of a touch (vibration) into an electronic signal.
This signal is then converted into an audio file, and then compared to preexisting audio profile for every position on the screen.
This system works without a grid of wires running through the screen, the touch screen itself is actually pure glass, giving it the optics and durability of the glass out of which it is made.
It works with scratches and dust on the screen, and accuracy is very good. It does not need a conductive object to activate it. It is a major advantage for larger displays.
As with the Dispersive Signal Technology system, after the initial touch this system cannot detect a motionless finger

Most popular Usage

Notebook computer lines featuring touchscreens
Toughbook series by Panasonic
ST series Stylistic tablets from Fujitsu
P series and T series notebooks from Fujitsu
C1 series notebook from LG
TouchSmart PCs from HP (really an All-in-One PC and not a notebook PC)
Latitude XT series by Dell


Applications

touchscreen is an input device that allows users to operate a PC by simply touching the display screen.
Touch input is suitable for a wide variety of computing applications.
A touchscreen can be used with most PC systems as easily as other input devices such as track balls or touch pads.

[attachment=4100]
TOUCH SCREEN
Definition
A touch screen is a computer display screen that is sensitive to human touch, allowing a user to interact with the computer by touching pictures or words on the screen.
Touch screen technology can be used as an alternative user interface with applications that normally require a mouse, such as a Web browser.
Some applications are designed specifically for touch screen technology, often having larger icons and links than the typical PC application.
Monitors are available with built-in touch screen technology or individuals can purchase a touch screen kit.

Touchscreen
Introduction
A Touchscreen is a display which can detect the location of touches within the display area. This allows the display to be used as an input device
mouse as the removing the keyboard and/or the primary input device for interacting with the display's content
Such displays can be attached to computers or, as terminals, to networks. Touchscreens also have assisted in recent changes in the design of personal digital assistant (PDA), satellite navigation and mobile phone devices, making these devices more usable.
Application

Touchscreens have become commonplace since the invention of the electronic touch interface in 1971 by Dr. Samuel C. Hurst.
They have become familiar in retail settings, on point of sale systems, on ATMs and on PDAs(personal digital assistant) sometimes used to manipulate the GUI and to enter data.
The HP-150 from 1983 was probably the world's earliest commercial touch screen computer.
It actually does not have a touch screen in the strict sense, but a 9" Sony CRT surrounded by infrared transmitters and receivers which detect the position of any non-transparent object on the screen.



Touchscreens are popular in heavy industry and in other situations, such as museum displays or room automation, where keyboards and mouse do not allow a satisfactory
the touchscreen sensor and its accompanying controller-based firmware have been made available by a wide array of after-market system integrators and not by display, chip or motherboard manufacturers
With time,display manufacturers and System On Chip (SOC) manufacturers worldwide have acknowledged the trend toward acceptance of touchscreens as a highly desirable user interface component and have begun to integrate touchscreen functionality into the fundamental design of their products.

A touch screen kit includes a touch screen panel, a controller, and a software driver.
The touch screen panel is a clear panel attached externally to the monitor that plugs into a serial or Universal Serial Bus (USB) port or a bus card installed inside the computer.
The touch screen panel registers touch events and passes these signals to the controller.
The controller then processes the signals and sends the data to the processor.
The software driver translates touch events into mouse events.
Drivers can be provided for both Windows and Macintosh operating systems.
Internal touch screen kits are available but require professional installation because they must be installed inside the monitor
Technology

Most Common types Of Touchscreen Technology
1. Resistive
2. Surface acoustic wave
3. Capacitive
4. Dispersive signal technology
5. Acoustic pulse recognition


Resistive
Resistive: A resistive touch screen panel is coated with a thin metallic electrically conductive and resistive layer that causes a change in the electrical current which is registered as a touch event and sent to the controller for processing. Resistive touch screen panels are generally more affordable but offer only 75% clarity and the layer can be damaged by sharp objects. Resistive touch screen panels are not affected by outside elements such as dust or water.

Surface acoustic wave
Surface wave: Surface wave technology uses ultrasonic waves that pass over the touch screen panel. When the panel is touched, a portion of the wave is absorbed. This change in the ultrasonic waves registers the position of the touch event and sends this information to the controller for processing. Surface wave touch screen panels are the most advanced of the three types, but they can be damaged by outside elements.

Capacitive
Capacitive: A capacitive touch screen panel is coated with a material that stores electrical charges. When the panel is touched, a small amount of charge is drawn to the point of contact. Circuits located at each corner of the panel measure the charge and send the information to the controller for processing. Capacitive touch screen panels must be touched with a finger unlike resistive and surface wave panels that can use fingers and stylus. Capacitive touch screens are not affected by outside elements and have high clarity.

Dispersive signal technology
Dispersive signal technology : Introduced in 2002, this system uses sensors to detect the mechanical energy in the glass that occur due to a touch.
Complex algorithms then interpret this information and provide the actual location of the touch.
The technology claims to be unaffected by dust and other outside elements, including scratches. Since there is no need for additional elements on screen, it also claims to provide excellent optical clarity.
Also, since mechanical vibrations are used to detect a touch event, any object can be used to generate these events, including fingers and styli.
A downside is that after the initial touch the system cannot detect a motionless finger.

Acoustic pulse recognition
Acoustic pulse recognition : This system uses more than two piezoelectric transducers located at some positions of the screen to turn the mechanical energy of a touch (vibration) into an electronic signal.
This signal is then converted into an audio file, and then compared to preexisting audio profile for every position on the screen.
This system works without a grid of wires running through the screen, the touch screen itself is actually pure glass, giving it the optics and durability of the glass out of which it is made.
It works with scratches and dust on the screen, and accuracy is very good. It does not need a conductive object to activate it. It is a major advantage for larger displays.
As with the Dispersive Signal Technology system, after the initial touch this system cannot detect a motionless finger

Most popular Usage

Notebook computer lines featuring touchscreens
Toughbook series by Panasonic
ST series Stylistic tablets from Fujitsu
P series and T series notebooks from Fujitsu
C1 series notebook from LG
TouchSmart PCs from HP (really an All-in-One PC and not a notebook PC)
Latitude XT series by Dell


Applications

touchscreen is an input device that allows users to operate a PC by simply touching the display screen.
Touch input is suitable for a wide variety of computing applications.
A touchscreen can be used with most PC systems as easily as other input devices such as track balls or touch pads.
[attachment=4100]

hi,..
its really awesome posting because its very helpful for many students,..
very nice sharing ,thanks,..

Thanks this is so helpful.

[attachment=10513]
INTRODUCING THE TECHNOLOGY
 A touch screen is an input device that allows users to operate a PC by simply touching the display screen.
 The display screen has a sensitive glass overlay placed on it and we could give the desired input by touching it.
 A touch screen is based on CRT (Cathode Ray Tube) technology, that accepts direct onscreen input.
 The ability for direct onscreen input is facilitated by an external (light pen) or an internal device (touch overlay and controller) .
HOW DOES A TOUCHSCREEN WORK?
Main touch screen components:
 Touch sensor
 Controller
 Software driver
TOUCH SENSOR
 A touch screen sensor is a clear glass panel with a touch responsive surface which is placed over a display screen so that the responsive area of the panel covers the viewable area of the display screen.
 The sensor generally has an electrical current or signal going through it and touching the screen causes a voltage or signal change. This voltage change is used to determine the location of the touch to the screen
CONTROLLER
 The controller is a small PC card that connects between the touch sensor and the PC. It takes information from the touch sensor and translates it into information that PC can understand.
SOFTWARE DRIVER
 The driver is a software that allows the touch screen and computer to work together. It tells the operating system how to interpret the touch event information that is sent from the controller.
 Most touch screen drivers today are a mouse-emulation type driver. This makes touching the screen the same as clicking your mouse at the same location on the screen.
TOUCH SCREEN DIVERSITY
 Resistive Touch screen
 Surface wave Touch screen
 Capacitive Touch screen
*Surface capacitive
*Projected capacitive
 Near Field Imaging Touch screen
 Infrared Touch screen
RESISTIVE TOUCH SCREEN
1. Polyester Film .
2. Top Resistive Layer.
3. Conductive Transparent Metal Coating.
4. Bottom Resistive Layer .
5. Insulating Dots .
6. Glass Substrate
 Resistive touch screen monitor is composed of a flexible top layer and a rigid bottom layer separated by insulating dots, attached to a touch screen controller.
 The inside surface of each of the two layers is coated with a transparent metal oxide coating
 Pressing the flexible top sheet creates electrical contact between the resistive layers, producing a switch closing in the circuit.
 The controller gets the alternating voltages between the two layers and converts them into the digital X and Y coordinates of the activated area.
VS20UA CONTROLLER
 Supply Voltage
5.0V DC
 Maximum Current
20mA (Pick)
 Resolution
12-bit
SURFACE WAVE TECHNOLOGY
 It has a transmitting and receiving transducers for both the X and Y axes.
 The touchscreen controller sends a 5 MHz electrical signal to the transmitting transducer, which converts the signal into ultrasonic waves within the glass.
 These waves are directed across the front surface of the touchscreen by an array of reflectors.
 Reflectors on the opposite side gather and direct the waves to the receiving transducer, which reconverts them into an electrical signal—a digital map of the touchscreen
 When you touch the screen, you absorb a portion of the wave traveling across it. The received signal is then compared to the stored digital map, the change recognized, and a coordinate calculated. . The digitized coordinates are transmitted to the computer for processing.
2701RSU CONTROLLER
 Voltaze
+5 VDC
 Baud Rate
9600 (default) and 19200
 Touch Resolution
12bit, size independent
 Conversion Time
10 s per coordinate set
CAPACITIVE TOUCH SCREENS
Surface Capacitive
 It has a an uniform conductive coating on a glass panel.
 During operation, electrodes around the panel's edge evenly distribute a low voltage across the conductive layer & creates an uniform electric field.
 A finger touch draws current from each corner.
 Then the controller measures the ratio of the current flow from the corners and calculates the touch location
5000 RSU SERIAL CONTROLLER
 Supply Voltage :
+5 V DC or +12V
 Baud Rate
9600 (default) and 19200
 Touch Resolution
12bit, size independent.
 Conversion Time
Approximately 15 ms per coordinate set
Projected Capacitive Touch screen
3layers:-front and back protective glass provides optical and strength enhancement options & middle layer consists of a laminated sensor grid of micro-fine wires
 During a touch, capacitance forms between the finger and the sensor grid.
 The embedded serial controller in the touch screen calculates touch location coordinates and transmits them to the computer for processing.
APPLICATIONS..
 Public Information Displays:::
Tourism displays, Trade show display
 Customer Self-Services:::
Stores, Restaurants, ATMs, Airline ticket terminals and Transportation hubs.
 More uses...
Digital jukeboxes, Computerized gaming, Student Registration systems, Multimedia softwares , Scientific applications etc.
Pros & Cons
 Direct pointing to the objects.
 Fast
 Finger or pen is usable (No cable required)
 No keyboard necessary
 Suited to: novices, application for information retrieval etc
 Low precision by using finger
 User has to sit or stand closer to the screen
 The screen may be covered more by using hand
 No direct activation to the selected function
CLOSING THOUGHTS
Though the touch screen technology contains some limitations it’s very user friendly, fast, accurate, easy for the novices & fun to operate. It has been widely accepted. And now by just modifying a little it can replace the mouse and key board completely in near future.

Submitted by:
Abhishek Tewari

---

[attachment=11761]
INTRODUCTION
A touch screen is an input device that allows users to operate a PC by simply touching the display screen.
The touch screen has two main attributes.
First it lets you interact directly with what is displayed.
Second directly with STYLUS.
There are 3 types of touch screen technologies:
Resistive touch screen
Surface acoustic wave
Capacitive touch screen
TYPES
1. RESISTIVE TOUCH SCREEN
2. CAPACITIVE TOUCH SCREEN
3. SURFACE ACOUSTIC WAVE TOUCH SCREEN
RESISTIVE TOUCH SCREEN
1. A resistive touch screen panel is composed of several layers.
2. Two thin, electrically conductive layers separated by a narrow gap.
3. When pressure is applied two metallic layers become connected at that point: the panel then behaves as a pair of voltage dividers with connected outputs.
4. This causes a change in the electrical current, which is registered as a touch event and sent to the controller for processing.
TYPES OF RESISTIVE TOUCH SCREENS
1. 4 WIRE RESITIVE
• Touch measurement in 4 Wire technology is a 2 step process.
• First the distance along the x axis at the point of touch is measured by creating a horizontal voltage gradient on the top sheet, with the bottom acting as the return layer.
• Second a vertical voltage gradient is created on the bottom layer, to measure the y axis.
DIFFERENT MODES FOR DETECTION
A touch-screen controller is simply an ADC that has built-in switches to control which electrodes are driven and which electrodes are used as the input to the ADC. The ADC can often be operated with different reference modes: single-ended or differential.
SINGLE ENDED CONFIGURATION
2. 5 WIRE RESISTIVE
In 5 Wire resistive, the main electronics are on the glass bottom layer. A uniform voltage is applied to the top plastic layer. A touch causes an electrical contact between the top and bottom layers. Depending on the point of touch the voltages at the 4 corners of the glass are different—these are measured, and used by a complex algorithm in the controller to calculate the x-y coordinate of the point of touch.
Resistive Touch Screen
Characters:
1. Cost effective solutions
2. Activated by a stylus, a finger or gloved hand
3. Not affected by dirt, dust, water, or light
4. 75%~85% clarify
5. Resistive layers can be damaged by a very sharp object.

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INTRODUCTION :
With the advent of the I-Phone, touch screen technology has reached the mainstream. Every call carrier now offers their own version of touch phones and there have been rumors of completely touch-interfaced computers. While touch screen technology has been around since the 1960’s, the media buzz has taken off in the past two to three years. Touch screen monitors have become more and more commonplace since their prices have dropped in the past decade. Touch screens are found in ATMs, PDAs, cellular phones, grocery checkout counters, airport check-in counters, and many other devices that we use every day.
Simply put, a touch screen is a display that can detect the presence and location of a touch within the display area. The term generally refers to touch or contact to the display of the device by a finger or hand. Touch screens provide an alternative user-interface to the historical mouse and keyboard of traditional computers.
Touch screens first became a research interest in the second half of the 1960’s. In 1971 Samuel Hurst developed the first “touch sensor.” One of the first places where they gained some visibility was in a computer-assisted learning terminal that came out in 1972 as part of the PLATO project. This was the first step in commercializing touch screen technologies. Touch screens became widely used in kiosk and point of sale systems in banks and stores. In 1983, the first touch screen computer, the HP-150, reached the market. Since then we have seen the introduction of advanced touch screen technologies leading to the commercialization of tablet PCs, PDAs, and touch-screen phones.
There are several different types of touch screen technology. The resistive system is based on the use of two parallel conductive and resistive metallic layers. The capacitive system uses a monitor with a built up charge on its surface. When a person touches the surface, the charge is transmitted to the user, thus allowing the computer to recognize the touch. A third technology is the surface acoustic wave. This recognizes touch by using transducers that can analyze at what instance a wave was disturbed.
In this presentation, we will touch on the history behind touch screen technology while also explaining in detail how the different methods of touch screen technologies work. More specifically, we will spend a considerable amount of time describing the different technologies found in devices that use touch screen. We will also delve into the current commercial applications and practical benefits of touch screens. Finally, we will comment on the future applications and potentials of touch screen technology.
HISTORY
The first touchscreen was a capacitive touch screen developed by E.A. Johnson at the Royal Radar Establishment, Malvern, UK. The inventor briefly described his work in a short article published in 1965 and then more fully - along with photographs and diagrams - in an article published in 1967. A description of the applicability of the touch technology for air traffic control was described in an article published in 1968.
Touchscreens first gained some visibility with the invention of the computer-assisted learning terminal, which came out in 1972 as part of the PLATO project. Touchscreens have subsequently become familiar in everyday life. Companies use touchscreens for kiosk systems in retail and tourist settings, point of sale systems, ATMs, and PDAs, where a stylus is sometimes used to manipulate the GUI and to enter data.
From 1979–1985, the Fairlight CMI was a high-end musical sampling and re-synthesis workstation that utilized light pen technology, with which the user could allocate and manipulate sample and synthesis data, as well as access different menus within its OS by touching the screen with the light pen. The later Fairlight series III models used a graphics tablet in place of the light pen.
The HP-150 from 1983 was one of the world's earliest commercial touchscreen computers. Similar to the PLATO IV system, the touch technology used employed Infrared transmitters and receivers mounted around the bezel of its 9" Sony Cathode Ray Tube (CRT), which detected the position of any non- transparent object on the screen.
An early attempt at a handheld game console with touchscreen controls was Sega’s intended successor to the Game Gear, though the device was ultimately shelved and never released due to the expensive cost of touchscreen technology in the early 1990s. Touchscreens would not be popularly used for video games until the release of the Nintendo DS in 2004.
Until recently, most consumer touchscreens could only sense one point of contact at a time, and few have had the capability to sense how hard one is touching. This is starting to change with the commercialization of multi-touch technology.
The popularity of smartphones, PDAs and tablet computers, portable video game consoles and many types of information appliances is driving the demand and acceptance of common touchscreens, for portable and functional electronics, with a display of a simple smooth surface and direct interaction without any hardware between the user and content, fewer accessories are required.
Touchscreens are popular in hospitality, and in heavy industry, as well as kiosks such as museum displays or room automation where keyboard and mouse systems do not allow a suitably intuitive, rapid, or accurate interaction by the user with the display's content.
Historically, the touchscreen sensor and its accompanying controller-based firmware have been made available by a wide array of after-market system integrators, and not by display, chip, or motherboard manufacturers. Display manufacturers and chip manufacturers worldwide have acknowledged the trend toward acceptance of touchscreens as a highly desirable user interface component and have begun to integrate touchscreen functionality into the fundamental design of their products.
CHAPTER 1 : RESISTIVE TOUCHSCREEN TECHNOLOGY
1.1 Introduction
Resistive touchscreens are touch sensitive computer displays composed of two flexible sheets coated with a resistive material and separated by an air gap or Microdots. The resistive coating is made up of Idium-Tin oxide. It is the most simple technology and hence it is widely used.
When contact is made with the surface of touchscreens, 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.
During the 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 uniform 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.
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.
Figure 1.1. Resistive touchscreen
1.2 Working
Figure 1.2. Working of Resistive touchscreens
The resistive touchscreens consist of two parallel sheets of resistive coating as mentioned earlier. If no external pressure is applied, then the two sheets are electrically separated. Hence the impedance between the two sheets remains the same.
But when an external pressure is applied, the distance between the two plates is lowered. As a result of this, the impedance between the two sheets is lowered at the touch point.
The top sheet carries a voltage gradient by applying a voltage between the electrodes of the top sheet. Whereas the bottom sheet serves as a slide in a linear potentiometer as shown.
Figure 1.3. Linear Potentiometer
Linear potentiometers are sensors that produce resistance output proportional to the displacement or position. Resistance value changes with the rotation of the screw.
Hence when we apply pressure on the touchscreen, the two sheets touch eachother. When a contact is established between the two sheets, a precise measurement of the touch point is made by first finding the X co-ordinate and then the Y co-ordinate.
1.3 Advantages
 It is the product of choice for the manufacturers because it can easily produce a resolution of 4096*4096 DPI or higher.
 They are low cost as compared to their ‘active’ counterparts.
 This technology can be produced to support multi-touch output.
 A sstylus or any pointed object can be utilized to operate such touchscreens.
 As its name implies, resistive touchscreens, are widely employed in environments such as hospital laboratories, factories and restaurants because these places contain liquids, chemicals and other contamination that can harm standard screens.
 A resistive touchscreen is very rugged and robust.
1.4 Disadvantages
 It is highly sensitive to high pressure.
 It is highly sensitive to 75% optical transparency.
New tablets are being developed to overcome these deficiencies that can differentiate between a stylus and human finger.