TOUCHSCREEN TECHNOLOGY

BY :-Ritanshu Goel

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

passive objects, such as a stylus.

The touchscreen has two main attributes:

1. It enables one to interact with what is displayed directly on the screen, where it is displayed, rather than indirectly with a mouse or touchpad.

2. It lets one do so without requiring any intermediate device, again, such as a stylus that needs to be held in the hand. Such displays can be attached to computers or, as terminals, to networks.

History

The first touch screen was a capacitive touch screen developed by E.A. Johnson at the Royal Radar Establishment, Malvern, UK. The inventor briefly described his work in a short article published in 1965 and then more fully - along with photographs and diagrams - in an article published in 1967.

One of the first places where they gained some visibility was in the terminal of a computer-assisted learning terminal that came out in 1972 as part of the PLATO project.

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

DevelopmentDevelopment

• The development of multipoint touchscreen facilitated the tracking of more than one finger on the screen, thus operations that require more than one finger are possible.

• These devices also allow multiple users to interact with the touchscreen simultaneously.

• With the influence of the multi-touch-enabled iPhone and the Nintendo DS, the touchscreen market for mobile devices produced 5 billion in 2009.

Touch screen technology

Main touch screen components:Main touch screen components: 1 Touch sensor 2 Controller 3 Software driver

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TOUCH SENSORTOUCH SENSOR..A touch sensor is a clear glass panel with a touch responsive

surface .

The sensor generally has an electrical signal going through it and touching the screen causing a signal change.

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

CONTROLLERCONTROLLER The controller is

small PC card that connects between the touch sensor and PC.

It takes information from the touch sensor and translate in to information that PC can understand.

SOFTWARE DRIVERSOFTWARE DRIVERThe driver is a software that allows the The driver is a software that allows the touch screen and computer to work touch screen and computer to work together.together.

It tells the operating system how to It tells the operating system how to interpret the touch event information that interpret the touch event information that sent from the controller.sent from the controller.

Most of the touch screen drivers today Most of the touch screen drivers today are are mousemouse emulation type driver emulation type driver . .

Construction

There are several principal ways to build a touchscreen:

• In the most popular techniques, the capacitive or resistive approach, manufactures coat the screen with a thin, transparent metallic layer.

• When a user touches the surface, the system records the change in the electrical current that flows through the display.

• Dispersive-signal technology which 3M created in 2002, measures the piezoelectric effect — the voltage generated when mechanical force is applied to a material — that occurs chemically when a strengthened glass substrate is touched.

TYPES OF TOUCHSCREEN

Resistive Touch screenSurface wave Touch screenCapacitive Touch screen

*Surface capacitive*Projected capacitive

Near Field Imaging Touch screenInfrared Touch screen

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Technologies

The types of technologies that can be found are asfollows:

Resistive:

●The resistive touch screen uses a glass panel with a uniform conductive ITO(Indium Tin Oxide) coating on the side surface.

●A PET film is a tightly suspended over the ITO coating surface of a glass panel.

Working Principle:

● When the screen is touched, it pushes the conductive ITO When the screen is touched, it pushes the conductive ITO coating on the PET film. That results the electrical contact, coating on the PET film. That results the electrical contact, producing the voltages. It presents the position touched.producing the voltages. It presents the position touched.

● Resistive touchscreen deliver cost-effective, consistent and durable performance

Surface Acoustic Wave:

• On the pure glass substrate, there are four piezoelectric transmitting and receiving transducers on the three corners for both the X and Y axes.

• 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 absorbs a portion of the wave passing across the surface of the panel.

• SAW can be used in any and all applications for the best possible image clarity an unlimited life.

Capacitive:

• Capacitive touchscreen is a four multi-layer glass.• Small amount of voltage is applied to the electrodes on

the four corners • A human body is an electric conductor, so when

touched the screen with a finger, a slight amount of current is drawn, creating a voltage drop. The current respectively drifts to the electrodes on the four corners.

• The capacitive system has very long life (about 225 million clicks).

Infrared:

• IR eliminates the use of glass or plastic overlay that most other touch technologies require in front of the display.

• High cost of the technology.

• IR increases the noise floor at the optical sensor

● Conventional optical-touch systems use an array of infrared (IR) light-emitting diodes (LEDs) on two adjacent bezel edges of a display, with photosensors placed on the two opposite bezel edges to analyze the system and determine a touch event.

Technology Capacitive SAW Infrared Resistive

Transparence 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

Advantages & Disadvantages:

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, Macintosh and Linux. • Does not interfere mouse and keyboard function. • Make computing easy, powerful and fun.

Disadvantages:

1)Finger stress: Stress on human fingers when used for more than a few minutes at a time. (for example, ATMs).

2)Fingerprints: Touchscreens can suffer from the problem of fingerprints on the display.

3)User has to sit closer to the screen as compared to external keyboard.

4) The screen may be covered more by using hand.

Applications

Public Access:•  Mobile Phones•  Library resource guides•  Computers•  Public Transportation Schedule / Status• Airport terminal passenger internet and

email systems• Automated travel and entertainment

ticket dispensers • Shopping mall directory

Business

•  Gas stations•  Point of sales• Restaurants•  Grocery stores• Hospital and hotel directories

(check-in, registration)•  Banks and Financial Reporting•  Bank cash advance and teller

machines

Conclusion:

• Designers are trying to use touchscreen to simplify input commands for largely unsophisticated computer users.

• Today, a larger 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 keyboards as they will be replaced by touchscreens.