SEMINAR

ON

TOUCH SCREENS

Presented by:- DILIP KUMAR

M110376CA NIT CALICUT

POINTS TO DISCUSS

● INTRODUCTION TO THE TECHNOLOGY● HISTORY AND DEVELOPMENT● CONSTRUCTION OF TOUCH SCREEN● TOCH TECHNOLOGIES● APPLICATIONS● CLOSING THOUGHTS● REFERENCES

INTRODUCTION

● A touch screen is computer display screen that is sensitive to human touch.

● It is the most user friendly input device used to interface with a PC.

● The display screen has a sensitive glass overlay placed on it and we could give the desired input by touching it.

● Touch screens can sense finger and other passive objects,

such as a stylus.

● A touch screen kit includes a touch screen panel, a controller and a software driver.

● A touch screen accepts direct onscreen inputs.

HISTORY AND DEVELOPMENT

● In 1971, the first “touch sensor” was developed by Dr. Sam

Hurst (founder of elographics) while he was an instructor at the university of Kentucky.

● In 1974 he developed the first real touch screen.

● The new transparent technology, Accu Touch , was later developed by the founders of Elographics, Dr. Hurst and Bill Colwell.

● Apple was the first with a touch screen phone in 1983.

● The nokia 7710 is a first touch screen mobile phone model produced by Nokia.

CONSTRUCTION OF TOUCH SCREEN

A basic touch screen has three main components -:

* A touch sensor

* A controller

* Software driver

The touch screen 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.

TOUCH SENSOR

● A touch sensor is a clear glass panel with a touch responsive surface.

● The touch sensor/panel is palced over a display screen so that the responsive area of the panel covers the viewable area of the video screen.

● The sensor generally has an electronic 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 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.

● The controller is usually installed inside the monitor for integrated monitor or it is housed in a plastic case for the external touch add-ons/overlays.

● Integrated touch monitor will have an extra cable connection on the back for the touch screen.Controllers are available that can connect to a serial/COM port(PC) or to a USB port.

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.

● Most touch screen drivers today are mouse-emulation type driver. This makes touching the screen the same as clicking mouse at the same location on the screen.

● This allows the touch screen to work with existing software and allows new applications to be developed without the need for the touch screen specific programming.

TOUCH TECHNOLOGIES

There are mainly 4 types of touch screen technologies -:

● Resistive

● Capacitive

● Surface acoustic wave

● Infrared

RESISTIVE TECHNOLOGY

● Respond to the pressure of a finger or stylus .

● When pressure is applied to the screen, the controller registers the touch event.

● Polyster film

● Top resistive layer

● Conductive transparent metal coating

● Bottom resistive layer

● Insulating dots

● Glass substrate.

ADVANTAGES & DISADVATGES

ADVANTAGES -:● Cost effective solution.

● Activated by any stylus.

● Very accurate

● Low power requirement.

● Liquids won't affect touch screen performance.

DISADVATAGES -:● Polyster surface can be damaged.

● Poor durability compared to other technologies.

CAPACITIVE TECHNOLOGY

● A capacitive touch screen panel is consists of an insulator such as glass, coated with a transparent conductor like indium tin oxide (ITO).

● In this a layer that stores electrical charge is placed on the glass panel.

● When a user touches , some of the charge is transferred to the user, so the charge on the capacitive layer decreases.

● This decrease is measured in electrodes located at each corner of monitor.

● The computer then calculates the coordinates, from the relative differences in charge at each corner. Then the controller measures the ratio of the current flow from the corners and calculate touch location.

ADVANTAGES -:

● More durable than resistive.

● Higher transmittance than resistive.

● High clarity.

● Scratch resistant .

DISADVATAGES -:

● Does not work with gloved finger or stylus.

● Accepts input from finger only.

● Accuracy is dependent on capacitance of person.

● Can be affected by electricity.

SURFACE WAVE TECHNOLOGY

● 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.

● This technology is used in ATMs, amusement parks, gaming environments, industrial control room etc.

ADVANTAGES -:● Very high transmittance.

● Very high durability.

● Fast touch response.

● Finger or gloved hand operation.

DISADVANTAGES -:● Must be touched by finger, gloved hand, or soft stylus.

Something hard like pen won't work.

● Can be affected by large amounts of grease, water, or dirt on the screen.

● Surface obstructions can cause a false touch.

INFRARED TECHNOLOGY

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.

ADVANTAGES -:● Mostly used in manufacturing and medical applications.

● Operated using a stylus or a gloved finger.

● More wear resistant.

● Very high durability and reliability.

● Can be activated with almost any device.

DISADVANTAGES -:● Lower resolution than other technologies.

● Surafce obstructions can cause a false touch.

● It is very sensitive and can be activated by stray touches.

APPLICATIONS

● Public information displays - tourism displays, trade show displays.

● Customer self services- stores,restaurents, transpotation hubs

ATM, airline e-ticket terminal.

● Computerized gaming

● Industrial process control.

● Home automation systems.

● Casino and other gaming systems.

● Computer access for the physically disabled people.

● Financial and scientific applications and more.

CLOSING THOUGHT

Though the touch screen technology contains some limitations it's very user friendly , fast, accurate and fun to operate. It has been widely accepted and now by just modifying a little it can replace the mouse and keyboard completely in near future.

REFERENCES

● Bent STUMPE (6 February 1978), Experiments to find a manufacturing process for an x-y touch screen, CERN, retrieved 2010-05-25

● "TapSense: Enhancing Finger Interaction on Touch Surfaces". Retrieved 28 January 2012.

● The first capacitative touch screens at CERN, CERN Courrier, 31 March 2010, retrieved 2010-05-25

● http://en.wikipedia.org/wiki/Touchscreen