Central Institute of Technology, Kokrajhar

Presentation on

Touch Screen Technology In Mobiles

Presented By:

Ajay Kachari Roll No: Gau-C-12/48

Sweta KritiRoll No: Gau-C-12/52

IntroductionA touch screen is an

electronic visual display that can detect the presence and location of a touch within the display area. Touch screens can sense Finger and other passive objects, such as a stylus. However, if the objects sensed is active, as with a light pen.

History and DevelopmentIn 1971 Dr. Samuel Hurst, founder of

Elographics developed the first touch sensor “Elograph” at the University of Kentucky.

In 1974, he developed the first real touch screen.

In 1977, Elographics developed the five-wire resistive technology a curved glass sensor called the Touch Screen.

The new transparent technology, AccuTouch, was later developed by the founder of Elographics, Dr. Hurst and Bill Colwell.

First Touch Phone:Apple was the first with a touch screen phone in 1983.

First Touch Mobile:The Nokia 7710 is the

first touch screen mobile phone model produced by Nokia.

Then they used it for the Nokia Symbian OSs.

Construction Of Touch ScreenA basic touch screen has three main components:A.A touch sensorB.A controllerC.A software driver

Touch SensorA touch 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.

ControllerThe controller is

a small PC card that connects between the touch sensor and the PC. It takes information from the touch sensor and translates into information that PC can understand

VS20UA ControllerSupply voltage: 5volt

Maximum current: 20mA(Pick)

Software DriverThe 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.

Types of Touch Technologies

There are mainly 4 types of touch technologies:

ResistiveSurface acoustic wave(SAW)CapacitiveInfrared

ResistiveA resistive touch screen

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, causes a change in the electrical current, which is registered as a touch event and sent to the controller for processing.

Advantages And Disadvantages of ResistiveAdvantages

Cost-effectiveActivated by any stylusVery accurateLow power requirementsLiquids won’t affect touch screen

performanceDisadvantages

Polyester surface can be damaged

Surface Acoustic Wave(SAW)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. The change in the ultrasonic waves registers the position of the touch event and sends this information to the controller for processing.

SAW touch screen technology is suggested for use in ATMs, Amusement Parks, Gaming Environments, Industrial Control Rooms etc.

Advantages and Disadvantages of SAWAdvantages

-Durable glass construction-High optical clarity-Activated by a finger, gloved hand, or soft tip stylus

Disadvantages-Moving liquids or condensation can cause false

touch-Solid contaminants create non-touches-Doesn’t support drag or draw effectively

CapacitiveA capacitive touch screen

panel consist 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

Advantages and Disadvantages Of Capacitive

Advantages-Scratch resistance, Durable surface-Very accurate-Good optical clarity -Liquid won’t affect touch screen

performanceDisadvantages

-Does not work with gloved fingers or stylus

Infrared An infrared touch

screen uses an array of X-Y infrared LED and photo detector pairs around the edges of the pattern of LED beams. Infra-red bezels have proven to be a very reliable technology for use in ATMs, Medical Instrumentation and Transportation Tracking applications.

Advantages and Disadvantages of Infrared Touch ScreenAdvantages

-Highest quality of underlying image-Very high transmittance-Can be activated with almost any device-Higher accuracy than other technologies-Very high durability and reliability

Disadvantages-It is very sensitive & can be activated by

stray touches-Low resolution

ManufactureApple was the first company

which introduce the touch phone and after that Nokia come into existence with their Nokia 7710. Now a days Nokia, Samsung, Sony Ericsson, Motorola, Blackberry are making touch screen technology. Some of the local companies are also taking part for making the touch technology but these are not effective in the environment.

Advantages of all Touch Technology

Touch screen have several advantages over other pointing devices:A touch screen is easy to use (as the user simply

touches what he or she sees on the display).Save space as no buttons are required.Touching a visual display of choices requires little

thinking and is a form of direct manipulation that is easy to learn.

Touch screens have easier hand eye coordination than buttons.

Touch screens are durable in public access and high volume usage.

Disadvantages of all Touch TechnologyScreen has to be really big not to miss things

when pressing them with finger. So the big screen leads to low battery life.

Touch screen means can’t be read too well in direct sunlight as it applies an additional not 100% transparent.

Touch screen devices usually has no additional keys and this means when an application crashes, without crashing the OS , you can’t get the main menu as the whole screen becomes unresponsive.

Screens get very dirty.

Thank You