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INTRODUCTIONINTRODUCTION

Invented by E.A. Johnson (Royal RadarEst.) around 1965 for air traffic control

1993 Apple’s Newton and IBM’s Simon

2002 Microsoft’s Windows XP Tablet

2007 Apple’s iPhone (Multi-touch)

The The HP-150HP-150 from 1983 was probably the world's from 1983 was probably the world's earliest commercial touchscreen computer using earliest commercial touchscreen computer using infrared technology.infrared technology.

Now days, Multipoint touchscreen facilitates the Now days, Multipoint touchscreen facilitates the tracking of more than one finger on the screen.tracking of more than one finger on the screen.

A Brief History

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

The controller is a small PC card that connects between the touch sensor and the PC

The controller determines what type of interface/connection you will need on the PC

A small PC card which translates

information that PC can understand.

The driver is a software that allows the touch screen and computer to work together

Most touch screen drivers today are a mouse-emulation type driver.

It tells the computer's o.s how to interpret the touch event information that is sent from the controller

Driver allows to work with existing

software.

Diagram showing the working

1.Resistive Touch Screen• A resistive A resistive

touchscreen panel is touchscreen panel is composed of several composed of several layers.layers.

• It consists of a glass It consists of a glass that is coated with that is coated with electrically conductive electrically conductive and resistive layers. and resistive layers.

Types of Touch screen Technologies

Composed of multiple layers separated by thin spaces

Using indium tin oxide (ITO) layers Different standards

4, 5, and 8 wire typesEach have advantages

Advantages:

Cost-effective and low power RequirementsActivated by any objectAccurate

Disadvantages:

Polyester surface can be damagedOnly 75% light transmissionLower endurance (~35 million touches)

Why Resistive?

2.Capacitive Touch Screen

It consist of a glass panel with capacitive (charge storing) material coating on its surface.

Circuits located at the corners of the screen measure capacitance of a person touching the overlay.

Consists of:Consists of:Insulator (glass or Air)Insulator (glass or Air)Conductive coating Conductive coating

(ITO)(ITO)

3.Surface Acoustic Wave Touchscreen

Surface wave technology uses ultrasonic wave that passes over the touch screen panel.

Widely used in application such as computer based training and information.

Surface consists of glass overlay with transmitting and receiving transducers

Electrical signals sent to the transmitting transducers converts to ultrasonic waves

Waves are directed across screen by reflectors then directed to receiving transducers

When finger touches screen it absorbs waves

4.Infrared Touch Screen The new generation

IR touchscreen LCD has been increased brightness, clarity and durability.

Touched with a finger, gloved hand, fingernail, or stylus, it delivers a fast, accurate response every time.

Uses infrared LEDs and matching photo detectors

Touching screen interrupts LEDs

Cameras detect reflected LED caused by touch

Controller able to calculate coordinates from camera data

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 software , Scientific applications etc.

Direct pointing to the objects.FastFinger or pen is usable (No cable required)No keyboard necessarySuited to: novices, application for information retrieval etc

Low precision by using fingerUser has to sit or stand closer to the screenThe screen may be covered more by using handNo direct activation to the selected function

Pros & Cons

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.Touchscreens can suffer from the problem of fingerprints on thedisplay. This can be mitigated by the use of materials withoptical coatings designed to reduce the visible effects offingerprint oils, such as the oleophobic coating used in theiPhone 3G, or by reducing skin contact by using a fingernail orstylus.