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 TOUCHY, Recently touch screen technology is increasingly gaining popularity as these can be seen at ATMs, cellphones. Touch screen based system allows an easy navigation around a graphic user interface based environment. As the technology advances, people may be able to operate computers without mouse and keyboards. The touch screen is an assistive technology. This interface can be beneficial to those that have difficulty in 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 in using computers. Currently various researches are being made to develop touch screen video projectors. This research will be throw light on significance of touch screen technology ,and discuss,compare these different technologies, focusing on the differences in types, as well as the positive and negative qualities.
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 screens are used with information kiosks, computer-based training devices, and systems designed to help individuals who have difficulty manipulating a mouse or keyboard.
Touch screen technology can be used as an alternate 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 personal computer application. Monitors are available with built-in touch screen technology or individuals can purchase a touch screen kit.
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 . And 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.
A BRIEF HISTORY OF TOUCH SCREENS :
Throughout the past century, technology has improved in many ways. The way in which humans interact with technology is one of the most important ways technology is changing. By using touch screen technology, the user is able to manipulate a digital environment by only the touch of their finger, or another input device, on the screen . Dr. G.S. Sam Hurst (left)
The first "touch sensor" was developed by Dr. Sam Hurst, founder of Elographics
while he was an instructor at the University of Kentucky in 1971. This sensor
was called the "Elograph", and was patented by The University of Kentucky
Research Foundation. The "Elograph" was not transparent as are touchscreens, but was a significant mile-stone for touch technology.
Figure 1:history of touch screen.
The first true touch screen came on the scene in 1974, again developed by
Dr.Hurst, of Elographics. In 1977, Elographics developed and patented five-wire
resistive technology, the most popular touch screen technology in use today. On
February 24, 1994, the company officially changed Its name from Elographics to
Elo TouchSystems. 
What is a touch screen ?
The term generally refers to touching the display of the device with a finger or hand.
The touch screen is the most user friendly PC interface. It is an input device, a way to communicate with the PC. The user touches the screen to select options presented on the screen. Associated hardware and software are used to determine the location of the press.Touch is the easiest to learn and use of any available interface. Businesses both large and small are using touch technology to create new products, reach new markets, increase productivity, and ease the flow of information.
These devices are "less than ideal for harsh environments", this is because they are Susceptible to temperature and humidity changes, which would affect the accuracy of the touch screen .This does not mean it does not lead constantly under standard conditions. One advantage of this technology is that the user will be unable to use his or her finger or a stylus as input devices . Generally, touch screen resistive very good performance, considering that it is cheaper than the touch screen are different.
â€¢ Touch screen enables people to use computers without any training.
â€¢ This technology is simple and user friendly.
â€¢ Touch screen provides fast access to any and all type of digital media.
â€¢ It ensures that no space is wasted as the input device is completely integrated into monitor.
â€¢ Touch screen provided sufficient security.
â€¢ Text can be displayed on variety of languages depending upon user needs.
â€¢ Although user friendly, touch screen cannot be used to enter large amount of data.
â€¢ This technology has not found in real world applications because system designers have not carefully considered how the system will function.
â€¢ Another failure of the industry has been not getting fast enough processing behind the buttons.
â€¢ A touch screen system will cost about two or three times of the amount of an existing keyboard display.
There are different types of touch screens have the advantage of different characteristics and differences. These differences resulted in different types of touch screen .
Types of touch screen are:
Resistant, amplitude and infrared .
A Resistant touch screen panel is composed of several layers, the most important of which
are two thin, 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 metallichttps://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcRiHFaipTEVjh81LVeqUEY_qii4U9uKWiJBSzxS3Q-WuFOGS23arQ
layers become connected at that point: This causes a change in the electrical current, which is
registered as a touch event and sent to the controller for processing. surface acoustic wave:
Surface acoustic wave (SAW) 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 can be damaged by outside elements. Contaminants on the surface can also interfere with the functionality of
the touch screen.
2- Amplitude :
amplitude touch screen panel is one which consists of an insulator such as glass, coated
with a transparent conductor such as indium tin oxide As the human body is also a
electrical conductor, touching the surface of the screen results in a distortion of the
screen's lectrostatic field, measurable as a change in capacitance. Different technologies may
be used to determine the location of the touch. The location is then sent to the controller for
3- Infrared :
An infrared touch screen uses an array of X-Y infrared LED and photo detector pairs
around the edges of the screen to detect a disruption in the pattern of LED beams. These
LED beams cross each other in vertical and horizontal patterns. This helps the sensors
pick up the exact location of the touch. A major benefit of such a system is that it can
detect essentially any input including a finger, gloved finger, stylus or pen. It is generally
used in outdoor applications and point of sale systems which can't rely on a conductor
(such as a bare finger) to activate the touch screen.
Touch Screen is widely used and emerging technology that is sensitive to human touch, allowing a user to interact with the computer by touching pictures or words on the screen. It provides a very good user interface with applications that normally require a mouse. Have also shown that users reached their fastest performance. During this experiment after only 25 minutes of practice. Although performance did not improve between the seventh and tenth trials, additional practice may result in even faster performance. A touch screen interface provides easy solutions to many problems. there will always be situations when limited quantities of free form text must be entered. In these situations a touch screen keyboard can be used. It has good future in many new technologies like in cell phones, palmtops, laptops etc.