touch screen technology

TOUCH SCREEN TECHNOLOGY

Contents1. Walkthrough2. Introduction3. Applications4. History, Evolution & Development5. Types of Touchscreen Technology

i. Resistiveii. Capacitiveiii. SAWiv. Infrared / Optical

6. Future Technology

Call it an effort of human

mind or a miracle from human heart but this is all happening with technology.

Just move the hand or walk your fingers over a thing and it works.

Yes, it is the interactive gesture based technology I am talking about.

Walkthrough

Introduction

A touch screen is an electronic visual display that detect the location and presence of touch in the display area

This works by locating the coordinates of users touch independent of what is being displayed on the screen

In today’s world, Touch Screen Technology is omnipresent

Starting from mobiles to home appliances almost all the electronic devices comprise TST

It allows users to interact directly with what is being displayed, rather than indirectly using an intermediate device like mouse or keyboard

Widely used in modern smartphones, video games, kiosks, navigation systems, etc.

Applications

History, Evolution & Development Invented by E.A. Johnson (Royal Radar Est.) around 1965 for air traffic control

HP-150 home computer using infrared technology in 1983

1993 Apple’s Newton and IBM’s Simon

2002 Microsoft’s Windows XP Tablet

2007 Apple’s iPhone (Multi-touch)

There are four main types of touchscreen technology namely:

1. Resistive2. Capacitive3. Surface Acoustic Wave (SAW)4. Infrared LED or Optical

Looking from an engineer’s perspective, this revolutionary touchscreen technology is a 2 dimensional sensing device made of 2 sheets of material separated by spacers

Types of Touchscreen Technology

Resistive Touchscreen Technology

A 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 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. It is used in Grocery Stores, Hotels, Restaurants and Retail Stores.

Advantages & Disadvantages

Advantages

1. Cost-effective solution

2. Activated by any stylus

3. Very accurate

4. Low power requirements

5. Liquids won't affect touch screen performance

Disadvantages

6. Polyester surface can be damaged

7. Lower endurance (35 million touches)

8” resistive touch screen will cost about $60

4 and 5 wire touch screens don’t need controllers For those that do, they cost less than $5

Any object can be used to activate the screen

Not able to register multiple touches

~75% of light is transferred through (12.5% per layer)

Some of the popular devices that use Resistive Touchscreen are Nintendo DS, Nokia N97, HTC Touch Pro2, HTC Tattoo, Sony Ericsson Satio, etc.

Summary

Capacitive Touchscreen Technology

A capacitive touch screen panel consists of an insulator such as glass, coated with a transparent conductor such as indium tin oxide (ITO)

Small amount of voltage applied to four corners of touch screen, draws minute amount of current creating voltage drop

Coordinates of point of contact calculated by controller

The capacitive systems transmit almost 90% of light from the monitor


Advantages

1. Scratch resistant, durable surface

2. High endurance (225 million touches)

3. Very accurate

4. Good optical clarity

5. Liquids won't affect touch screen performance

Disadvantages

1. Does not work with gloved fingers or stylus

Summary 8” capacitive touch screen costs about $100

Controllers can be bought for less than $5

Only conductive objects can be used to activate

Able to register multiple touches

~88% of light is transferred through Some of the devices using capacitive touchscreen are

Motorola Xoom, Samsung Galaxy Tab, Samsung Galaxy SII, Apple’s iPad

Surface Acoustic Wave Touchscreen Technology

The Surface Acoustic Wave Touchscreen technology contains two transducers (transmitting and receiving) placed along the X-axis and Y-axis of the monitor’s glass plate along with some reflectors.

When the screen is touched, the waves are absorbed and a touch is

detected at that point. These reflectors reflect all electrical signals sent from one transducer to another.

This technology provides excellent throughput and image clarity.

The waves propagate across the glass and are reflected back to the sensors.


Advantages

1. Durable glass construction

2. High optical clarity

3. Activated by a finger, gloved hand, or soft tip stylus

Disadvantages

4. Moving liquids or condensation can cause false touches

5. Solid contaminants create non-touch areas until removed

6. Doesn't support drag or draw effectively

7. Expensive

Summary

Prices for individual screens are unavailable



~100% of light is transferred through SAW touch screen technology is suggested for use in ATMs, Amusement Parks, Gaming Environments, Industrial Control Rooms etc

Infrared Touchscreen Technology

An infrared touch screen uses an array of X-Y infrared LED and photo detector pairs around the edges of the screen to detect a disruption in the pattern of LED beams.

Touching screen interrupts LEDs

Cameras detect reflected LED caused by touch

Controller able to calculate coordinates from camera data

Advantages & DisadvantagesAdvantages

1. Highest quality of underlying image

2. Very high transmittance

3. Excellent anti-glare, with use of chemically etched glass

4. Can be activated with almost any device

5. Higher accuracy than other technologies

6. Very high durability and reliability

Disadvantages

7. Surface obstructions can cause a false touch

8. It is very sensitive and can be activated by stray touches.

9. Low resolution

10. Parallax problems

Summary

Infra-red bezels have proven to be a very reliable technology for use in ATMs, Medical Instrumentation and Transportation Tracking applications

8” infrared touch screen costs about $160



~100% of light is transferred through

Touch Screen Technology Comparison Chart

Future of Touchscreen Technology Touchscreen Technology has made a tremendous progress in the past few years and the future beholds a lot of surprising innovations

As complex the technology gets as simpler the life becomes and there we would be.

Closing Thoughts

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.

*References

*Wikipedia *www.engineersgarage.com/articles/*www.computerworld.com/.../how-it-works--

the-technology-of-touch-scr...

http://www.computerworld.com/.../how-it-works--the-technology-of-touch-scr

http://www.computerworld.com/.../how-it-works--the-technology-of-touch-scr

Thank you :D