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SEMINAR

ON

MULTI TOUCH

PRESENTED BY

Rahul kumar

GUIDED BYPreetha M kurup


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OVERVIEW

> Introduction.

> Technologies.

> Comparison of touch screen.> Advantages & Disadvantages.

> Applications.

> Future Touchscreen technology.> conclusion.


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INTRODUCTION

> A touchscreen 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.

> Touchscreen can also sense other passiveobjects, such as a stylus.


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Continues.

The touchscreen has two main attributes:

1: It enables one to interact with what is displa-ed directly on the screen , where it is display-

ed, rather than indirectly with a mouse or to-

uchpad.

2: It lets one do so without requiring any inter-

mediate device, again , such as stylus that

needs to be held in the hand. Such displayscan be attached to computers or, as termin-

als, to networks.


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History

> Touchscreen 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 co-

puter-assisted learning terminal that cameout in 1972 as part of the PLATO project.


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Continues

> The HP-150 from 1983 was probably the

worlds earliest commercial touchscreen

computer.

> It doesnt actually have a touchscreen in the

strict sense , but a sony CRT surrounded by

infrared transmitters and receivers which

detect the position of any non-transparent

object on the screen.


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Development

The development of multipoint touchscreen

facilitated the tracking of more than one fin-

ger on the screen, thus operations that requ-

ire more than one finger are possible.

These devices also allow multiple users to

interact with the touchscreen simultaneou-sly.


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Construction

There are several principal ways to build a

touchscreen:

In the most popular techniques, the capaci-

tive or resistive approach, manufactures

coat the screen with a thin, transparent me-

talic layer.


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Continues..

When a user touch the surface, the systemrecord the change in the electrical current

that flows through the display.

Dispersive signal technology which 33MMcreated in 2002, measures the piezoelectric

effect the voltage generated when mecha-

nical force is applied to a material - that

occure chemically when a strengthened glasssubstrate is touched.


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Continues

There are two infrared-based approaches.

An array of sensors detects a finger touching

or almost touching the display, there by int-

errupting ligh t beams projected over the

screen. Bottom-mounted infrared cameras record

screen touches.

In the case, the system determine the inte-nded command based on the controls sho-

wing on the screen at the time and the loc-

ation of the touch.


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Technologies

The type of technologies that can be foundare follows:

Resistive:

The resistive toucch screen

uses a glass panel with auniform conductive ITO

(Indiu m Tin Oxide) coating

on the side surface.

A PET film is a tightly suspe-nded over the ITO coating

surface of a glass panel.


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Continues

The microprocessor applies +5V to pin (X left) on

the glass pane l, and the voltage is uniformly dec-

reasing to pin (X right) for 0V because of the resi-

stive ITO coating on the glass substrate , and the

PET film is grounded.

When the touchscreen is touched, a voltage on the

glass substrate proportional to the X position of the

toch appears on the PET film


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Continues.

this voltage is digitized by the A/D converter and su-

bjected to an averaging algorithm. Then it is stored

and trasfered to the host. Hance , the X position is

produced. The next electric cycle , Y position is

produced.

Resistive touchsceen deliver cost-effective, consist-

ent and durable peroemance.

Resistive technology include only 75% optical tran-

sparency and the fact that as harp object can dam-

age the resistive layers.


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Continues

The SAW controller sends a 5 MHZ electrical signal

to the X-axis and Y-axis transmitting transducers.

When the touchscreen is touched, the finger abso-

rbs of the wave passing across the surface of the

panel.

SAW can be used in any and all application for the

best clarity an unlimited life.


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Capacitive:

Capacitive touchscreen is a four multi-layer glass


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Continues.

Small amount of voltage is applied to the electrodes

on the four corners.

A human body is an electric conductor, So when to-

uched the screen with a finger, a slight amount of

current is drawn, creating a voltage drop. The curr-

ent respectively drifts to the electrodes on the four

corners.

The capacitive system has very long life (about 225

million clicks).


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Infrared:

Conventionaloptical touch

systems use an array of in-

frared ( IR ) light emitting

diodes (LEDs) on two adj-acent bezel edges of a dis-

play , with photosensors

placed on the two opposite

bezel edge to analyze thesystem and determine a to-

uch event.


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Continues

IR eliminates the use of glass or plastic overlay that

most other touch technologies require in front ofthe display.

High cost of the technology.

IR increases the noise floor at the optical sensor.


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Coparison of Technolges:

Technology Resistive SAW Infrared Capacitive

Durability: 5 years 5 years 3 years 2 years

Stability: High Higher High Ok

Transparency: Ok Good Good Ok

Touch: Anything Finger/pen Sharp Conductive

Response

time:


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Advantages & Diadvantages:

Advantages: User friendly.

Fast response.

Error free input.

Easy to install.

Use finger, fingernail,gloved hand, stylus or any

soft-tip pointer to operate.

Easy to clean and maintain.

Compatible with windows, Macitosh and linux.

Does not interfere mouse and keybord function.

Make computing easy, powerful and fun.


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Diadvantages:

Finger stress:

stress on human fingers when used for more thana few minutes at a time (for examlpe, ATMs).

Fingerprints:

Touchscreens can suffer from the problem of finger

prints on the display.


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Applications

Public Access:

Museums.

Library resource guides. Corporate information.

Public transportation schedule/status.

Airport terminals passenger internet and email

systems. Automated travel and entertainment ticket disp-

nsers.

Shopping mall directory.


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Continues.

Business:

Gas stations.

Point of sales.

Resturants.

Grocery stores.

Books and Financial Reporting.

bank cash advance and teller machines.


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Continues

Entertainment: Interactive computer games.

Casinos.

Government:

Military control system. Scientific research lab.


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FutureThe use of multi-touch technology is expected to rapidly

become common place. For example, touch screen telep-

hone. The multi touch can be used including:

Enhanced dining experience. concierge service.

Governmental use.

Concept mapping.

Collaboration and instruction on Interactive whitebo-ards.


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Conclusion:

Designers are trying to use touchscreen to simplify

input commands for largely unsophisticated comp-

uter users.

Today, a large share of population is PC literate, yet

the touchscreen has become adopted by computer

users of all abilities because it is simple, fast, and

innovative.

In future there is no usage of mouse and keyboard

as they will be replaced by touchscreens.


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References:

http://en.wikipedia.org/wiki/touchscreen

Research Note on multi-touch screen sensor

by Andrew Nathanson

http://www.wisegeek.com/what-are-touch -

screen-monitors.htm

http://www.billbuxton.com/multitouch

Overview.html

How to build a multi touch by Harry Vaan Der


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