touch screen tech.pptx

TOUCH SCREEN TECHNOLOGY

Presented by:Bharti Panjwani

POINTS OF DISCUSSION

Introduction History & Development Touch Screen Technology

Touch Sensor Controller Software driver

Different type of Touch Technology Resistive touch screen Capacitive touch screen Infrared touch screen Surface acoustic wave (SAW) touch screen Optical imaging touch screen Dispersive signal technology touch screen

Comparison of Touch Technology Applications Advantages and Disadvantages Future scope References

TOUCH SCREEN

A touch screen is an electronic visual display that can detect the presence and location of a touch within the display area.

It can sense the presence of finger or stylus on the screen.

It’s a input device that allows user to interact with the system.

TOUCH SCREEN

A Touch Screen has 2 main attributes:

It enables user to interact directly with what is displayed, rather than indirectly with a pointer controlled by a mouse or touchpad.

By using touch screen technology, the user is able to manipulate a digital environment by only the touch of their finger.

HISTORY AND DEVELOPMENT

Dr Samuel Hurst is known to be the Father of touch screen technology.

In 1971, he invented first touch screen based on resistive technology and that device was called Elo-graph which was used for research and industrial applications.

1n 1982, hp invented first touch Screen computer which had infrared touch screen capability allowing use of it in ATM like applications.

CONT…

Multi‐touch technology also began in 1982, this system used a frosted‐glass panel with a camera placed behind the glass.

In 1985, came a multi‐touch tablet that used capacitance rather than bulky camera‐based sensing systems.

In 2007, Microsoft released its Microsoft Surface and Apple unveiled the iPhone.

FIRST TOUCH PHONE

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

FIRST TOUCH MOBILE

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

It is Nokia's first smart phone to run GUI a top the Symbian OS.

TOUCH SCREEN MOBILES

TOUCH SCREEN TECHNOLOGY

A touch screen is an input device that allows users to operate by simply touching the display screen.

It needs to be combined with a display or PC to form complete touch input system.

A touch screen is technology to accept direct onscreen input.

A basic touch screen has three main components:

Touch Sensor

Controller

Software driver

TOUCH SENSOR A touch screen sensor is a clear glass

panel with a touch responsive surface.

The touch sensor/panel is placed over a display screen so that it covers the viewable area of the video screen.

The sensor generally has an electrical current or signal going through it and touching the screen can cause a voltage or signal change.

This change in the signal is used to determine the location of the touch in the screen.

CONTROLLER

The controller connects the touch sensor and the PC.

It takes information from the touch sensor and translates it into information that PC can understand.

Controllers are available that can connect to a Serial/COM port or to a USB port.

SOFTWARE DRIVER

The driver 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 a mouse-emulation type driver. This makes touching the screen as same as clicking mouse at the same location on the screen.

TOUCH SCREEN TECHNOLOGIES

Various Technologies based on methods of sensing the touch

Resistive touch screen Capacitive touch screen Infrared touch screen Surface acoustic wave (SAW) touch screen Optical imaging touch screen Dispersive signal technology touch screen

RESISTIVE TOUCH SCREEN

There are two thin electrically conductive and resistive layers made with Indium Tin oxide(ITO), 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 metallic 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.

RESISTIVE TOUCH SCREEN

4-WIRE RESISTIVE TOUCH SCREEN

ADVANTAGES & DISADVANTAGES

AdvantagesCost-effective solutionActivated by any stylusVery accurateLow power requirements

DisadvantagesSurface can be damaged by sharp

objectsLower endurance (35 million touches)

CAPACITIVE TOUCH SCREEN

This touch screen makes use of change in capacitance for determination of location of touch.

There can be 2 types of capacitive touch screen depending upon their construction:

Surface Capacitive Touch ScreenProjected Capacitive Touch Screen

SURFACE-CAPACITIVE TOUCH SCREEN

Surface capacitive technology consists of a uniform conductive coating on one side of glass panel.

Electrodes around the panel’s edge evenly distribute a low voltage across the conductive layer, creating a uniform electric field.

When a conductor such as human finger touches the non-conducting side of panel a capacitor is dynamically formed.

SURFACE-CAPACITIVE TOUCH SCREEN

SURFACE-CAPACITIVE TOUCH SCREEN

The touch to the screen with a finger, draws a slight amount of current, creating a voltage drop.

The current respectively drifts to the electrodes on the four corners.

SURFACE-CAPACITIVE TOUCH SCREEN

Theoretically, the amount of current that drifts through the four electrodes should be proportional to the distance from the touch point to the four corners.

The controller precisely calculates the proportion of the current passed through the four electrodes and figures out the X/Y coordinate of a touch point.

PROJECTED-CAPACITIVE TOUCH SCREEN

Projected capacitive touchscreens have front and back protective glass providing optical and strength enhancement.

Its middle layer consists of conductive grid of micro-fine wires in form of matrix.

Voltage given to these grid electrodes creates a uniform electrostatic field.

PROJECTED-CAPACITIVE TOUCH SCREEN

During a touch, capacitance forms between the finger and the sensor grid.

The embedded serial controller in the touch screen calculates touch location coordinates and transmits them to the computer for processing.

SURFACE VS. PROJECTED

Limited resolution Single touch Operation with

direct contact

High resolution Multi touch Operation with

indirect contact

ADVANTAGES & DISADVANTAGES

AdvantagesScratch resistant, durable surfaceVery accurate and faster responseHigh endurance (225 million touches)Superior optical clarity and brighter

display

DisadvantagesDoes not work with gloved fingers or

stylusProne to false signals because of parasitic

capacitive coupling

INFRARED TOUCH SCREENS

An infrared touch screen uses:

An array of infrared LED around the edges of the screen to create a grid of invisible infrared light.

An array of photo detector  to detect a disruption in the pattern of LED beams.

INFRARED TOUCH SCREENS

When a stylus, such as a finger, enters the grid, it obstructs the beams.

One or more photo transistors from each axis detect the absence of light and transmit signals to the controller which calculates the x and y coordinates.

ADVANTAGES & DISADVANTAGES

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

DisadvantagesIt is very sensitive and can be activated by

stray touches.Parallax problems

SURFACE ACOUSTIC 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 and this change in waves is used to find the location of touch.

ADVANTAGES & DISADVANTAGES

AdvantagesHigh optical clarityDurable glass constructionActivated by a finger, gloved hand, or stylus

DisadvantagesSolid contaminants create non-touch areas until removed

Doesn't support drag or draw effectively

OPTICAL IMAGING TOUCH SCREEN

Optical Touch Screen consists of two or more optical sensors placed around the corners of the screen.

OPTICAL IMAGING TOUCH SCREEN

Infrared backlights are placed in the sensor's field of view on the other sides of the screen to project a uniform field of infrared light.

A touch shows up as a shadow and each pair of optical sensors can locate the touch or even measure the size of the touching object.

FEATURES OF OPTICAL IMAGING TECHNOLOGY

This technology comes as two, three or four camera solutions, providing dual and multi-touch functionality.

Optical sensors used to detect the touch point, so the touch registers just before the physical touch on the screen. This means that users can apply zero or light touch to the screen to initiate a response.

Optical imaging scales to very large displays (120 inches), making it possible to create genuinely collaborative, interactive conference and teaching settings.

ADVANTAGES & DISADVANTAGES

AdvantagesTechnique scales to very large displaysFunctions with scratches and surface wearTouch activated by bare or gloved finger, stylus

DisadvantagesMoving liquids or solid contaminants may

cause false touches or non-function surface until completely removed

System thickness is typically 3.5 mm in addition to the thickness of the glass

TOUCH SCREEN TECHNOLOGY COMPARISON

Technology Capacitive SAW Infrared Resistive

Transparency Very good >92%

Very good >92%

Very good >92%

75%~85%

Resolution Good Good Limited due tospacing of IRsensors

good

SurfaceContaminants/durability

Resistant tomoisture andother surfacecontaminants

Adversely affected bymoisture orSurfacecontaminants

Potential forFalse activationor dead zonesFrom SurfaceContaminants

Unaffected by Surfacecontaminants.Polyester topsheet is easilyscratched

Sensor substrate Glass with ITO coating

Glass with ITO coating

Any substrate Polyester top sheet, glasssubstrate withITO coating

Display size 8.4"-21" 10.4"-30" 10.4"-60" up to 19"

Touch method Human touch finger, gloved

hand or soft tip Can use any pointing device

Can use any pointing device

APPLICATIONS OF TOUCH SCREENS 

Informational kiosks ATM and BanksMuseum / tourism displaysIndustrial process controls Cell Phones and iPhones Home automation systems Gaming systems Computer access for the physically disabled

ADVANTAGES OF TOUCH TECHNOLOGY

Touch screens 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 it acts as both input and output device.

Touch screens have easier hand eye coordination than buttons and thus are faster.

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

DISADVANTAGES OF TOUCH TECHNOLOGY

Big screen leads to low battery life. Screens get very dirty with continuous touches. These devices require massive computing

power which leads to slow devices. Touch screen means screen can’t be read too

well in direct sunlight as it is not 100% transparent.

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

FUTURE OF TOUCH TECHNOLOGY Further developments in touch screen technology

includes what is considered as an interactive touch screen.

Printing Polymer Transistors onto flexible plastic displays is under research. It could be used to develop “bendier”, slim, power saving, low cost touch screens.

There is a estimation that the global market for touch screen mobiles will account for 80 per cent of all global mobile sales by 2013.

CLOSING THOUGHTS

One definition of sustainability is the improvement of the quality of life by making life more enjoyable and less burdensome.

Touch screen technology fits within this definition very well. Touch screens are very user friendly, fast, accurate, flexible, easy & fun to operate.It has been widely accepted. And it can replace the mouse and key board completely in near future.

REFERENCES

Timothy Hoye and Joseph Kozak “Touch Screens:

A Pressing Technology” Tenth Annual Freshman Conference April. 2010

Nichols, Steven J. Vaughan “New Interfaces at the Touch of a Fingertip” IEEE Society August. 2007

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

Thank You